diff --git a/CMakeLists.txt b/CMakeLists.txt
index 84d564b297..8ed4bcb61e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -46,14 +46,9 @@ find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS
     UiTools
     Widgets
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    find_package(Qt6 ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS X11Extras)
-    find_package(Qt6XkbCommonSupport REQUIRED)
-else()
-    find_package(Qt6 ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS WaylandClient ShaderTools)
-    if (Qt6WaylandClient_VERSION VERSION_LESS "6.4.1") # TODO Plasma 6: Drop once minimum Qt version is 6.4.1+
-        include(Qt6WaylandClientMacrosKde)
-    endif()
+find_package(Qt6 ${QT_MIN_VERSION} CONFIG REQUIRED COMPONENTS WaylandClient ShaderTools)
+if (Qt6WaylandClient_VERSION VERSION_LESS "6.4.1") # TODO Plasma 6: Drop once minimum Qt version is 6.4.1+
+    include(Qt6WaylandClientMacrosKde)
 endif()
 
 find_package(Qt${QT_MAJOR_VERSION}Test ${QT_MIN_VERSION} CONFIG QUIET)
@@ -210,14 +205,6 @@ set_package_properties(PlasmaWaylandProtocols PROPERTIES
     URL "https://invent.kde.org/libraries/plasma-wayland-protocols/"
 )
 
-if (QT_MAJOR_VERSION EQUAL "5")
-    find_package(QtWaylandScanner)
-    set_package_properties(QtWaylandScanner PROPERTIES
-        TYPE REQUIRED
-        PURPOSE "Required for building KWin with Wayland support"
-    )
-endif()
-
 find_package(XKB 0.7.0)
 set_package_properties(XKB PROPERTIES
     TYPE REQUIRED
@@ -313,14 +300,6 @@ set_package_properties(X11_XCB PROPERTIES
     TYPE OPTIONAL
 )
 
-# dependencies for QPA plugin
-if (QT_MAJOR_VERSION EQUAL "5")
-    find_package(Qt6FontDatabaseSupport REQUIRED)
-    find_package(Qt6ThemeSupport REQUIRED)
-    find_package(Qt6ServiceSupport REQUIRED)
-    find_package(Qt6EventDispatcherSupport REQUIRED)
-endif()
-
 find_package(Freetype)
 set_package_properties(Freetype PROPERTIES
     DESCRIPTION "A font rendering engine"
diff --git a/autotests/CMakeLists.txt b/autotests/CMakeLists.txt
index aaadf7210a..567f8aaab3 100644
--- a/autotests/CMakeLists.txt
+++ b/autotests/CMakeLists.txt
@@ -51,6 +51,7 @@ set_target_properties(testClientMachine PROPERTIES COMPILE_DEFINITIONS "NO_NONE_
 
 target_link_libraries(testClientMachine
     Qt::Concurrent
+    Qt::GuiPrivate
     Qt::Test
     Qt::Widgets
 
@@ -62,11 +63,6 @@ target_link_libraries(testClientMachine
 
     ${X11_X11_LIB} # to make jenkins happy
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testClientMachine Qt::X11Extras)
-else()
-    target_link_libraries(testClientMachine Qt::GuiPrivate)
-endif()
 add_test(NAME kwin-testClientMachine COMMAND testClientMachine)
 ecm_mark_as_test(testClientMachine)
 
@@ -76,6 +72,7 @@ ecm_mark_as_test(testClientMachine)
 add_executable(testXcbWrapper test_xcb_wrapper.cpp xcb_scaling_mock.cpp)
 
 target_link_libraries(testXcbWrapper
+    Qt::GuiPrivate
     Qt::Test
     Qt::Widgets
 
@@ -84,11 +81,6 @@ target_link_libraries(testXcbWrapper
 
     XCB::XCB
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testXcbWrapper Qt::X11Extras)
-else()
-    target_link_libraries(testXcbWrapper Qt::GuiPrivate)
-endif()
 add_test(NAME kwin-testXcbWrapper COMMAND testXcbWrapper)
 ecm_mark_as_test(testXcbWrapper)
 
@@ -96,6 +88,7 @@ if (XCB_ICCCM_FOUND)
     add_executable(testXcbSizeHints test_xcb_size_hints.cpp xcb_scaling_mock.cpp)
     set_target_properties(testXcbSizeHints PROPERTIES COMPILE_DEFINITIONS "NO_NONE_WINDOW")
     target_link_libraries(testXcbSizeHints
+        Qt::GuiPrivate
         Qt::Test
         Qt::Widgets
 
@@ -105,11 +98,6 @@ if (XCB_ICCCM_FOUND)
         XCB::ICCCM
         XCB::XCB
     )
-    if (QT_MAJOR_VERSION EQUAL "5")
-        target_link_libraries(testXcbSizeHints Qt::X11Extras)
-    else()
-        target_link_libraries(testXcbSizeHints Qt::GuiPrivate)
-    endif()
     add_test(NAME kwin-testXcbSizeHints COMMAND testXcbSizeHints)
     ecm_mark_as_test(testXcbSizeHints)
 endif()
@@ -120,6 +108,7 @@ endif()
 add_executable(testXcbWindow test_xcb_window.cpp xcb_scaling_mock.cpp)
 
 target_link_libraries(testXcbWindow
+    Qt::GuiPrivate
     Qt::Test
     Qt::Widgets
 
@@ -128,11 +117,6 @@ target_link_libraries(testXcbWindow
 
     XCB::XCB
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testXcbWindow Qt::X11Extras)
-else()
-    target_link_libraries(testXcbWindow Qt::GuiPrivate)
-endif()
 add_test(NAME kwin-testXcbWindow COMMAND testXcbWindow)
 ecm_mark_as_test(testXcbWindow)
 
@@ -213,6 +197,7 @@ target_link_libraries(testXkb
     kwin
 
     Qt::Gui
+    Qt::GuiPrivate
     Qt::Test
     Qt::Widgets
 
@@ -223,11 +208,6 @@ target_link_libraries(testXkb
 
     XKB::XKB
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testXkb Qt6::XkbCommonSupportPrivate)
-else()
-    target_link_libraries(testXkb Qt::GuiPrivate)
-endif()
 add_test(NAME kwin-testXkb COMMAND testXkb)
 ecm_mark_as_test(testXkb)
 
diff --git a/autotests/integration/CMakeLists.txt b/autotests/integration/CMakeLists.txt
index 9f09686646..9342154c62 100644
--- a/autotests/integration/CMakeLists.txt
+++ b/autotests/integration/CMakeLists.txt
@@ -1,61 +1,23 @@
 add_subdirectory(helper)
 
 add_library(KWinIntegrationTestFramework SHARED)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
-        BASENAME input-method-unstable-v1
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml
-        BASENAME text-input-unstable-v3
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL protocols/wlr-layer-shell-unstable-v1.xml
-        BASENAME wlr-layer-shell-unstable-v1
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
-        BASENAME xdg-shell
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/xdg-decoration/xdg-decoration-unstable-v1.xml
-        BASENAME xdg-decoration-unstable-v1
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
-        BASENAME idle-inhibit-unstable-v1
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-device-v2.xml
-        BASENAME kde-output-device-v2
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-management-v2.xml
-        BASENAME kde-output-management-v2
-    )
-    ecm_add_qtwayland_client_protocol(KWinIntegrationTestFramework
-        PROTOCOL ${WaylandProtocols_DATADIR}/staging/fractional-scale/fractional-scale-v1.xml
-        BASENAME fractional-scale-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(KWinIntegrationTestFramework
-        NO_INCLUDE_CORE_ONLY
-        FILES
-            ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
-    )
-    qt6_generate_wayland_protocol_client_sources(KWinIntegrationTestFramework
-        FILES
-            ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml
-            ${CMAKE_CURRENT_SOURCE_DIR}/protocols/wlr-layer-shell-unstable-v1.xml
-            ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
-            ${WaylandProtocols_DATADIR}/unstable/xdg-decoration/xdg-decoration-unstable-v1.xml
-            ${WaylandProtocols_DATADIR}/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
-            ${WaylandProtocols_DATADIR}/staging/fractional-scale/fractional-scale-v1.xml
-            ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-device-v2.xml
-            ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-management-v2.xml
-    )
-endif()
+
+qt6_generate_wayland_protocol_client_sources(KWinIntegrationTestFramework
+    NO_INCLUDE_CORE_ONLY
+    FILES
+        ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
+)
+qt6_generate_wayland_protocol_client_sources(KWinIntegrationTestFramework
+    FILES
+        ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml
+        ${CMAKE_CURRENT_SOURCE_DIR}/protocols/wlr-layer-shell-unstable-v1.xml
+        ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
+        ${WaylandProtocols_DATADIR}/unstable/xdg-decoration/xdg-decoration-unstable-v1.xml
+        ${WaylandProtocols_DATADIR}/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
+        ${WaylandProtocols_DATADIR}/staging/fractional-scale/fractional-scale-v1.xml
+        ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-device-v2.xml
+        ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-output-management-v2.xml
+)
 
 target_sources(KWinIntegrationTestFramework PRIVATE
     ../../src/cursor.cpp
diff --git a/autotests/integration/globalshortcuts_test.cpp b/autotests/integration/globalshortcuts_test.cpp
index f14c4b80ef..1871bda61a 100644
--- a/autotests/integration/globalshortcuts_test.cpp
+++ b/autotests/integration/globalshortcuts_test.cpp
@@ -102,23 +102,17 @@ void GlobalShortcutsTest::testNonLatinLayout_data()
 
     QTest::newRow("Left Ctrl + Tab") << KEY_LEFTCTRL << Qt::CTRL << KEY_TAB << Qt::Key_Tab;
     QTest::newRow("Left Ctrl + W") << KEY_LEFTCTRL << Qt::CTRL << KEY_W << Qt::Key_W;
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     QTest::newRow("Left Ctrl + `") << KEY_LEFTCTRL << Qt::CTRL << KEY_GRAVE << Qt::Key_QuoteLeft;
-#endif
 
     QTest::newRow("Left Alt + Tab") << KEY_LEFTALT << Qt::ALT << KEY_TAB << Qt::Key_Tab;
     QTest::newRow("Left Alt + W") << KEY_LEFTALT << Qt::ALT << KEY_W << Qt::Key_W;
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     QTest::newRow("Left Alt + `") << KEY_LEFTALT << Qt::ALT << KEY_GRAVE << Qt::Key_QuoteLeft;
-#endif
 
     QTest::newRow("Left Shift + Tab") << KEY_LEFTSHIFT << Qt::SHIFT << KEY_TAB << Qt::Key_Tab;
 
     QTest::newRow("Left Meta + Tab") << KEY_LEFTMETA << Qt::META << KEY_TAB << Qt::Key_Tab;
     QTest::newRow("Left Meta + W") << KEY_LEFTMETA << Qt::META << KEY_W << Qt::Key_W;
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     QTest::newRow("Left Meta + `") << KEY_LEFTMETA << Qt::META << KEY_GRAVE << Qt::Key_QuoteLeft;
-#endif
 }
 
 void GlobalShortcutsTest::testNonLatinLayout()
@@ -403,13 +397,6 @@ void GlobalShortcutsTest::testSetupWindowShortcut()
     QVERIFY(dialog->isInternal());
     auto sequenceEdit = workspace()->shortcutDialog()->findChild<QKeySequenceEdit *>();
     QVERIFY(sequenceEdit);
-
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    // the QKeySequenceEdit field does not get focus, we need to pass it focus manually
-    QEXPECT_FAIL("", "Edit does not have focus", Continue);
-    QVERIFY(sequenceEdit->hasFocus());
-    sequenceEdit->setFocus();
-#endif
     QTRY_VERIFY(sequenceEdit->hasFocus());
 
     quint32 timestamp = 0;
diff --git a/autotests/libkwineffects/CMakeLists.txt b/autotests/libkwineffects/CMakeLists.txt
index 0bd07c699d..109735ece8 100644
--- a/autotests/libkwineffects/CMakeLists.txt
+++ b/autotests/libkwineffects/CMakeLists.txt
@@ -17,7 +17,4 @@ kwineffects_unit_tests(
 add_executable(kwinglplatformtest kwinglplatformtest.cpp mock_gl.cpp ../../src/libkwineffects/kwinglplatform.cpp)
 add_test(NAME kwineffects-kwinglplatformtest COMMAND kwinglplatformtest)
 target_link_libraries(kwinglplatformtest Qt::Test Qt::Gui KF6::ConfigCore XCB::XCB)
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(kwinglplatformtest Qt::X11Extras)
-endif()
 ecm_mark_as_test(kwinglplatformtest)
diff --git a/autotests/tabbox/CMakeLists.txt b/autotests/tabbox/CMakeLists.txt
index 592e09cde3..e12fed3f32 100644
--- a/autotests/tabbox/CMakeLists.txt
+++ b/autotests/tabbox/CMakeLists.txt
@@ -31,9 +31,6 @@ target_link_libraries(testTabBoxClientModel
 
     XCB::XCB
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testTabBoxClientModel Qt::X11Extras)
-endif()
 add_test(NAME kwin-testTabBoxClientModel COMMAND testTabBoxClientModel)
 ecm_mark_as_test(testTabBoxClientModel)
 
@@ -68,9 +65,6 @@ target_link_libraries(testTabBoxHandler
 
     XCB::XCB
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(testTabBoxHandler Qt::X11Extras)
-endif()
 add_test(NAME kwin-testTabBoxHandler COMMAND testTabBoxHandler)
 ecm_mark_as_test(testTabBoxHandler)
 
diff --git a/autotests/tabbox/test_tabbox_clientmodel.cpp b/autotests/tabbox/test_tabbox_clientmodel.cpp
index 32e3091769..00669279ba 100644
--- a/autotests/tabbox/test_tabbox_clientmodel.cpp
+++ b/autotests/tabbox/test_tabbox_clientmodel.cpp
@@ -12,11 +12,8 @@
 #include "mock_tabboxhandler.h"
 
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
+
 using namespace KWin;
 
 void TestTabBoxClientModel::initTestCase()
diff --git a/autotests/tabbox/test_tabbox_handler.cpp b/autotests/tabbox/test_tabbox_handler.cpp
index c696376a60..2ad9c31d6c 100644
--- a/autotests/tabbox/test_tabbox_handler.cpp
+++ b/autotests/tabbox/test_tabbox_handler.cpp
@@ -10,11 +10,7 @@
 #include "clientmodel.h"
 #include "mock_tabboxhandler.h"
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 using namespace KWin;
 
diff --git a/autotests/test_client_machine.cpp b/autotests/test_client_machine.cpp
index 1cfc36739c..89d533cd76 100644
--- a/autotests/test_client_machine.cpp
+++ b/autotests/test_client_machine.cpp
@@ -13,11 +13,7 @@
 // Qt
 #include <QApplication>
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 // xcb
 #include <xcb/xcb.h>
 // system
diff --git a/autotests/test_x11_timestamp_update.cpp b/autotests/test_x11_timestamp_update.cpp
index 0f9383cc0a..f6f5ca07ea 100644
--- a/autotests/test_x11_timestamp_update.cpp
+++ b/autotests/test_x11_timestamp_update.cpp
@@ -8,11 +8,7 @@
 */
 
 #include <QTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 #include "main.h"
 #include "utils/common.h"
diff --git a/autotests/test_xcb_size_hints.cpp b/autotests/test_xcb_size_hints.cpp
index e1d4da84b7..884aa206af 100644
--- a/autotests/test_xcb_size_hints.cpp
+++ b/autotests/test_xcb_size_hints.cpp
@@ -12,11 +12,7 @@
 // Qt
 #include <QApplication>
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 #include <netwm.h>
 // xcb
 #include <xcb/xcb.h>
diff --git a/autotests/test_xcb_window.cpp b/autotests/test_xcb_window.cpp
index 173f15ba9e..86ec824d0f 100644
--- a/autotests/test_xcb_window.cpp
+++ b/autotests/test_xcb_window.cpp
@@ -12,11 +12,7 @@
 // Qt
 #include <QApplication>
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 // xcb
 #include <xcb/xcb.h>
 
diff --git a/autotests/test_xcb_wrapper.cpp b/autotests/test_xcb_wrapper.cpp
index 6eaa41005a..472a7273c7 100644
--- a/autotests/test_xcb_wrapper.cpp
+++ b/autotests/test_xcb_wrapper.cpp
@@ -12,11 +12,7 @@
 // Qt
 #include <QApplication>
 #include <QtTest>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 #include <netwm.h>
 // xcb
 #include <xcb/xcb.h>
diff --git a/autotests/test_xkb.cpp b/autotests/test_xkb.cpp
index f99bfcfc80..a737637b10 100644
--- a/autotests/test_xkb.cpp
+++ b/autotests/test_xkb.cpp
@@ -133,13 +133,8 @@ static const TransKey g_rgQtToSymX[] = {
     {XKB_KEY_XF86AudioNext, Qt::Key_MediaNext, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86AudioRecord, Qt::Key_MediaRecord, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86Mail, Qt::Key_LaunchMail, Qt::KeyboardModifiers()},
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     {XKB_KEY_XF86MyComputer, Qt::Key_LaunchMedia, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86Calculater, Qt::Key_Calculator, Qt::KeyboardModifiers()},
-#else
-    {XKB_KEY_XF86MyComputer, Qt::Key_Launch0, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Calculator, Qt::Key_Launch1, Qt::KeyboardModifiers()},
-#endif
     {XKB_KEY_XF86Memo, Qt::Key_Memo, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86ToDoList, Qt::Key_ToDoList, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86Calendar, Qt::Key_Calendar, Qt::KeyboardModifiers()},
@@ -241,7 +236,6 @@ static const TransKey g_rgQtToSymX[] = {
     {XKB_KEY_XF86TouchpadOn, Qt::Key_TouchpadOn, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86TouchpadOff, Qt::Key_TouchpadOff, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86AudioMicMute, Qt::Key_MicMute, Qt::KeyboardModifiers()},
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     {XKB_KEY_XF86Launch0, Qt::Key_Launch0, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86Launch1, Qt::Key_Launch1, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86Launch2, Qt::Key_Launch2, Qt::KeyboardModifiers()},
@@ -258,22 +252,6 @@ static const TransKey g_rgQtToSymX[] = {
     {XKB_KEY_XF86LaunchD, Qt::Key_LaunchD, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86LaunchE, Qt::Key_LaunchE, Qt::KeyboardModifiers()},
     {XKB_KEY_XF86LaunchF, Qt::Key_LaunchF, Qt::KeyboardModifiers()},
-#else
-    {XKB_KEY_XF86Launch0, Qt::Key_Launch2, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch1, Qt::Key_Launch3, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch2, Qt::Key_Launch4, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch3, Qt::Key_Launch5, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch4, Qt::Key_Launch6, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch5, Qt::Key_Launch7, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch6, Qt::Key_Launch8, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch7, Qt::Key_Launch9, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch8, Qt::Key_LaunchA, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86Launch9, Qt::Key_LaunchB, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86LaunchA, Qt::Key_LaunchC, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86LaunchB, Qt::Key_LaunchD, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86LaunchC, Qt::Key_LaunchE, Qt::KeyboardModifiers()},
-    {XKB_KEY_XF86LaunchD, Qt::Key_LaunchF, Qt::KeyboardModifiers()},
-#endif
 
      // Latin-1
     {XKB_KEY_exclam, Qt::Key_Exclam, Qt::KeyboardModifiers()},
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 09cb97aec4..17624c2b9e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -227,9 +227,6 @@ target_link_libraries(kwin
     Wayland::Server
     lcms2::lcms2
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(kwin Qt6::X11Extras Qt6::XkbCommonSupportPrivate)
-endif()
 
 if (KWIN_BUILD_NOTIFICATIONS)
     target_link_libraries(kwin KF6::Notifications)
diff --git a/src/backends/x11/standalone/CMakeLists.txt b/src/backends/x11/standalone/CMakeLists.txt
index 294402ff28..79f93c12ff 100644
--- a/src/backends/x11/standalone/CMakeLists.txt
+++ b/src/backends/x11/standalone/CMakeLists.txt
@@ -19,9 +19,6 @@ set(X11PLATFORM_SOURCES
 
 add_library(KWinX11Platform OBJECT ${X11PLATFORM_SOURCES})
 target_link_libraries(KWinX11Platform kwin KF6::Crash X11::X11 XCB::XKB PkgConfig::XKBX11)
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(KWinX11Platform Qt::X11Extras)
-endif()
 if (X11_Xi_FOUND)
     target_sources(KWinX11Platform PRIVATE x11_standalone_xinputintegration.cpp)
     target_link_libraries(KWinX11Platform X11::Xi)
diff --git a/src/backends/x11/standalone/x11_standalone_backend.cpp b/src/backends/x11/standalone/x11_standalone_backend.cpp
index 86e837f046..bcbaddbbd7 100644
--- a/src/backends/x11/standalone/x11_standalone_backend.cpp
+++ b/src/backends/x11/standalone/x11_standalone_backend.cpp
@@ -45,11 +45,7 @@
 
 #include <QOpenGLContext>
 #include <QThread>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 #include <span>
 
diff --git a/src/backends/x11/standalone/x11_standalone_effects_keyboard_interception_filter.cpp b/src/backends/x11/standalone/x11_standalone_effects_keyboard_interception_filter.cpp
index 9211fef877..6cf824f002 100644
--- a/src/backends/x11/standalone/x11_standalone_effects_keyboard_interception_filter.cpp
+++ b/src/backends/x11/standalone/x11_standalone_effects_keyboard_interception_filter.cpp
@@ -10,11 +10,7 @@
 
 #include <QDebug>
 #include <QKeyEvent>
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtXkbCommonSupport/private/qxkbcommon_p.h>
-#else
 #include <QtGui/private/qxkbcommon_p.h>
-#endif
 
 namespace KWin
 {
diff --git a/src/backends/x11/standalone/x11_standalone_egl_backend.cpp b/src/backends/x11/standalone/x11_standalone_egl_backend.cpp
index 15e2097029..b48f4ef74b 100644
--- a/src/backends/x11/standalone/x11_standalone_egl_backend.cpp
+++ b/src/backends/x11/standalone/x11_standalone_egl_backend.cpp
@@ -20,9 +20,6 @@
 #include "x11_standalone_overlaywindow.h"
 
 #include <QOpenGLContext>
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtPlatformHeaders/QEGLNativeContext>
-#endif
 #include <drm_fourcc.h>
 
 namespace KWin
@@ -97,17 +94,6 @@ void EglBackend::init()
     EGLContext shareContext = EGL_NO_CONTEXT;
     if (qtShareContext) {
         qDebug(KWIN_X11STANDALONE) << "Global share context format:" << qtShareContext->format();
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        const QVariant nativeHandle = qtShareContext->nativeHandle();
-        if (!nativeHandle.canConvert<QEGLNativeContext>()) {
-            setFailed(QStringLiteral("Invalid QOpenGLContext::globalShareContext()"));
-            return;
-        } else {
-            QEGLNativeContext handle = qvariant_cast<QEGLNativeContext>(nativeHandle);
-            shareContext = handle.context();
-            shareDisplay = handle.display();
-        }
-#else
         const auto nativeHandle = qtShareContext->nativeInterface<QNativeInterface::QEGLContext>();
         if (nativeHandle) {
             shareContext = nativeHandle->nativeContext();
@@ -116,7 +102,6 @@ void EglBackend::init()
             setFailed(QStringLiteral("Invalid QOpenGLContext::globalShareContext()"));
             return;
         }
-#endif
     }
     if (shareContext == EGL_NO_CONTEXT) {
         setFailed(QStringLiteral("QOpenGLContext::globalShareContext() is required"));
diff --git a/src/backends/x11/standalone/x11_standalone_glx_backend.cpp b/src/backends/x11/standalone/x11_standalone_glx_backend.cpp
index 163731c2bd..bfa5589aec 100644
--- a/src/backends/x11/standalone/x11_standalone_glx_backend.cpp
+++ b/src/backends/x11/standalone/x11_standalone_glx_backend.cpp
@@ -39,14 +39,7 @@
 // Qt
 #include <QDebug>
 #include <QOpenGLContext>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtPlatformHeaders/QGLXNativeContext>
-#endif
 // system
 #include <unistd.h>
 
@@ -350,16 +343,6 @@ bool GlxBackend::initRenderingContext()
     GLXContext globalShareContext = nullptr;
     if (qtGlobalShareContext) {
         qDebug(KWIN_X11STANDALONE) << "Global share context format:" << qtGlobalShareContext->format();
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        const QVariant nativeHandle = qtGlobalShareContext->nativeHandle();
-        if (!nativeHandle.canConvert<QGLXNativeContext>()) {
-            qCDebug(KWIN_X11STANDALONE) << "Invalid QOpenGLContext::globalShareContext()";
-            return false;
-        } else {
-            QGLXNativeContext handle = qvariant_cast<QGLXNativeContext>(nativeHandle);
-            globalShareContext = handle.context();
-        }
-#else
         const auto nativeHandle = qtGlobalShareContext->nativeInterface<QNativeInterface::QGLXContext>();
         if (nativeHandle) {
             globalShareContext = nativeHandle->nativeContext();
@@ -367,7 +350,6 @@ bool GlxBackend::initRenderingContext()
             qCDebug(KWIN_X11STANDALONE) << "Invalid QOpenGLContext::globalShareContext()";
             return false;
         }
-#endif
     }
     if (!globalShareContext) {
         qCWarning(KWIN_X11STANDALONE) << "QOpenGLContext::globalShareContext() is required";
diff --git a/src/backends/x11/standalone/x11_standalone_omlsynccontrolvsyncmonitor.cpp b/src/backends/x11/standalone/x11_standalone_omlsynccontrolvsyncmonitor.cpp
index f2cc54aaca..f27ba1c751 100644
--- a/src/backends/x11/standalone/x11_standalone_omlsynccontrolvsyncmonitor.cpp
+++ b/src/backends/x11/standalone/x11_standalone_omlsynccontrolvsyncmonitor.cpp
@@ -8,11 +8,7 @@
 #include "x11_standalone_glxconvenience.h"
 #include "x11_standalone_logging.h"
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 namespace KWin
 {
diff --git a/src/backends/x11/standalone/x11_standalone_sgivideosyncvsyncmonitor.cpp b/src/backends/x11/standalone/x11_standalone_sgivideosyncvsyncmonitor.cpp
index 9e247b0678..c2b7ce8940 100644
--- a/src/backends/x11/standalone/x11_standalone_sgivideosyncvsyncmonitor.cpp
+++ b/src/backends/x11/standalone/x11_standalone_sgivideosyncvsyncmonitor.cpp
@@ -8,11 +8,7 @@
 #include "x11_standalone_glxconvenience.h"
 #include "x11_standalone_logging.h"
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 namespace KWin
 {
diff --git a/src/composite.cpp b/src/composite.cpp
index eefc8a7a2b..ca2d389965 100644
--- a/src/composite.cpp
+++ b/src/composite.cpp
@@ -325,11 +325,7 @@ bool Compositor::setupStart()
 
     if (!Workspace::self() && m_backend && m_backend->compositingType() == QPainterCompositing) {
         // Force Software QtQuick on first startup with QPainter.
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        QQuickWindow::setSceneGraphBackend(QSGRendererInterface::Software);
-#else
         QQuickWindow::setGraphicsApi(QSGRendererInterface::Software);
-#endif
     }
 
     Q_EMIT sceneCreated();
diff --git a/src/effectloader.cpp b/src/effectloader.cpp
index 7f5aa37ab1..ed95c4cf88 100644
--- a/src/effectloader.cpp
+++ b/src/effectloader.cpp
@@ -163,11 +163,7 @@ void ScriptedEffectLoader::queryAndLoadAll()
             m_queryConnection = QMetaObject::Connection();
         },
         Qt::QueuedConnection);
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    watcher->setFuture(QtConcurrent::run(this, &ScriptedEffectLoader::findAllEffects));
-#else
     watcher->setFuture(QtConcurrent::run(&ScriptedEffectLoader::findAllEffects, this));
-#endif
 }
 
 QList<KPluginMetaData> ScriptedEffectLoader::findAllEffects() const
diff --git a/src/effects/mouseclick/mouseclick.cpp b/src/effects/mouseclick/mouseclick.cpp
index 05fabb1e08..603dd5c70d 100644
--- a/src/effects/mouseclick/mouseclick.cpp
+++ b/src/effects/mouseclick/mouseclick.cpp
@@ -331,18 +331,6 @@ bool MouseClickEffect::tabletToolEvent(QTabletEvent *event)
     auto &tabletEvent = m_tabletTools[event->uniqueId()];
     if (!tabletEvent.m_color.isValid()) {
         switch (event->pointerType()) {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        case QTabletEvent::UnknownPointer:
-        case QTabletEvent::Pen:
-            tabletEvent.m_color = MouseClickConfig::color1();
-            break;
-        case QTabletEvent::Eraser:
-            tabletEvent.m_color = MouseClickConfig::color2();
-            break;
-        case QTabletEvent::Cursor:
-            tabletEvent.m_color = MouseClickConfig::color3();
-            break;
-#else
         case QPointingDevice::PointerType::Unknown:
         case QPointingDevice::PointerType::Generic:
         case QPointingDevice::PointerType::Finger:
@@ -355,7 +343,6 @@ bool MouseClickEffect::tabletToolEvent(QTabletEvent *event)
         case QPointingDevice::PointerType::Cursor:
             tabletEvent.m_color = MouseClickConfig::color3();
             break;
-#endif
         }
     }
     switch (event->type()) {
diff --git a/src/effects/private/expolayout.cpp b/src/effects/private/expolayout.cpp
index 55e87d27dc..b0c3704368 100644
--- a/src/effects/private/expolayout.cpp
+++ b/src/effects/private/expolayout.cpp
@@ -314,20 +314,12 @@ void ExpoLayout::removeCell(ExpoCell *cell)
     polish();
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-void ExpoLayout::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
-#else
 void ExpoLayout::geometryChange(const QRectF &newGeometry, const QRectF &oldGeometry)
-#endif
 {
     if (newGeometry.size() != oldGeometry.size()) {
         polish();
     }
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QQuickItem::geometryChanged(newGeometry, oldGeometry);
-#else
     QQuickItem::geometryChange(newGeometry, oldGeometry);
-#endif
 }
 
 static int distance(const QPoint &a, const QPoint &b)
diff --git a/src/effects/private/expolayout.h b/src/effects/private/expolayout.h
index 1fb7af3b2a..895aff7099 100644
--- a/src/effects/private/expolayout.h
+++ b/src/effects/private/expolayout.h
@@ -50,11 +50,7 @@ public:
     Q_INVOKABLE void forceLayout();
 
 protected:
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override;
-#else
     void geometryChange(const QRectF &newGeometry, const QRectF &oldGeometry) override;
-#endif
     void updatePolish() override;
 
 Q_SIGNALS:
diff --git a/src/helpers/killer/CMakeLists.txt b/src/helpers/killer/CMakeLists.txt
index 182788708d..bca6afebee 100644
--- a/src/helpers/killer/CMakeLists.txt
+++ b/src/helpers/killer/CMakeLists.txt
@@ -8,12 +8,8 @@ target_link_libraries(kwin_killer_helper
     KF6::AuthCore
     KF6::I18n
     KF6::WidgetsAddons
+    Qt::GuiPrivate
     Qt::Widgets
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(kwin_killer_helper Qt::X11Extras)
-else()
-    target_link_libraries(kwin_killer_helper Qt::GuiPrivate)
-endif()
 
 install(TARGETS kwin_killer_helper DESTINATION ${KDE_INSTALL_LIBEXECDIR})
diff --git a/src/helpers/killer/killer.cpp b/src/helpers/killer/killer.cpp
index 9f1a58d93a..ed103997a5 100644
--- a/src/helpers/killer/killer.cpp
+++ b/src/helpers/killer/killer.cpp
@@ -12,11 +12,7 @@
 #include <QCommandLineParser>
 #include <QDebug>
 #include <QProcess>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 #include <xcb/xcb.h>
 
 #include <cerrno>
diff --git a/src/input_event.cpp b/src/input_event.cpp
index 65fa7168fb..1e32ded3da 100644
--- a/src/input_event.cpp
+++ b/src/input_event.cpp
@@ -64,7 +64,6 @@ SwitchEvent::SwitchEvent(State state, std::chrono::microseconds timestamp, Input
 {
 }
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 TabletEvent::TabletEvent(Type t, const QPointingDevice *dev, const QPointF &pos, const QPointF &globalPos,
                          qreal pressure, float xTilt, float yTilt,
                          float tangentialPressure, qreal rotation, float z,
@@ -73,16 +72,5 @@ TabletEvent::TabletEvent(Type t, const QPointingDevice *dev, const QPointF &pos,
     , m_id(tabletId)
 {
 }
-#else
-TabletEvent::TabletEvent(Type t, const QPointF &pos, const QPointF &globalPos,
-                         int device, int pointerType, qreal pressure, int xTilt, int yTilt,
-                         qreal tangentialPressure, qreal rotation, int z,
-                         Qt::KeyboardModifiers keyState, qint64 uniqueID,
-                         Qt::MouseButton button, Qt::MouseButtons buttons, const TabletToolId &tabletId)
-    : QTabletEvent(t, pos, globalPos, device, pointerType, pressure, xTilt, yTilt, tangentialPressure, rotation, z, keyState, uniqueID, button, buttons)
-    , m_id(tabletId)
-{
-}
-#endif
 
 }
diff --git a/src/input_event.h b/src/input_event.h
index 9981eeac9b..5389879600 100644
--- a/src/input_event.h
+++ b/src/input_event.h
@@ -210,18 +210,10 @@ public:
 class TabletEvent : public QTabletEvent
 {
 public:
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     TabletEvent(Type t, const QPointingDevice *dev, const QPointF &pos, const QPointF &globalPos,
                 qreal pressure, float xTilt, float yTilt,
                 float tangentialPressure, qreal rotation, float z,
                 Qt::KeyboardModifiers keyState, Qt::MouseButton button, Qt::MouseButtons buttons, const TabletToolId &tabletId);
-#else
-    TabletEvent(Type t, const QPointF &pos, const QPointF &globalPos,
-                int device, int pointerType, qreal pressure, int xTilt, int yTilt,
-                qreal tangentialPressure, qreal rotation, int z,
-                Qt::KeyboardModifiers keyState, qint64 uniqueID,
-                Qt::MouseButton button, Qt::MouseButtons buttons, const TabletToolId &tabletId);
-#endif
 
     const TabletToolId &tabletId() const
     {
diff --git a/src/libkwineffects/CMakeLists.txt b/src/libkwineffects/CMakeLists.txt
index a49cde8534..02d90c8f93 100644
--- a/src/libkwineffects/CMakeLists.txt
+++ b/src/libkwineffects/CMakeLists.txt
@@ -42,13 +42,11 @@ target_link_libraries(kwineffects
         KF6::WindowSystem
         XCB::XCB
     PRIVATE
+        Qt::GuiPrivate
         Qt::Quick
         KF6::I18n
         kwinglutils
 )
-if (QT_MAJOR_VERSION EQUAL "6")
-    target_link_libraries(kwineffects PRIVATE Qt::GuiPrivate)
-endif()
 set_target_properties(kwineffects PROPERTIES
     VERSION ${KWINEFFECTS_VERSION}
     SOVERSION ${KWINEFFECTS_SOVERSION}
diff --git a/src/libkwineffects/kwinoffscreenquickview.cpp b/src/libkwineffects/kwinoffscreenquickview.cpp
index ef9ab825fd..36b2c3ed01 100644
--- a/src/libkwineffects/kwinoffscreenquickview.cpp
+++ b/src/libkwineffects/kwinoffscreenquickview.cpp
@@ -26,12 +26,10 @@
 #include <QOpenGLContext>
 #include <QOpenGLFramebufferObject>
 #include <QTimer>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <QQuickGraphicsDevice>
 #include <QQuickOpenGLUtils>
 #include <QQuickRenderTarget>
 #include <private/qeventpoint_p.h> // for QMutableEventPoint
-#endif
 
 namespace KWin
 {
@@ -83,14 +81,8 @@ public:
     bool m_visible = true;
     bool m_automaticRepaint = true;
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QList<QTouchEvent::TouchPoint> touchPoints;
-    Qt::TouchPointStates touchState;
-    QTouchDevice *touchDevice;
-#else
     QList<QEventPoint> touchPoints;
     QPointingDevice *touchDevice;
-#endif
 
     ulong lastMousePressTime = 0;
     Qt::MouseButton lastMousePressButton = Qt::NoButton;
@@ -147,11 +139,7 @@ OffscreenQuickView::OffscreenQuickView(QObject *parent, QWindow *renderWindow, E
     if (!usingGl) {
         qCDebug(LIBKWINEFFECTS) << "QtQuick Software rendering mode detected";
         d->m_useBlit = true;
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        d->m_renderControl->initialize(nullptr);
-#else
         d->m_renderControl->initialize();
-#endif
     } else {
         QSurfaceFormat format;
         format.setOption(QSurfaceFormat::ResetNotification);
@@ -170,12 +158,8 @@ OffscreenQuickView::OffscreenQuickView(QObject *parent, QWindow *renderWindow, E
         d->m_offscreenSurface->create();
 
         d->m_glcontext->makeCurrent(d->m_offscreenSurface.get());
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        d->m_renderControl->initialize(d->m_glcontext.get());
-#else
         d->m_view->setGraphicsDevice(QQuickGraphicsDevice::fromOpenGLContext(d->m_glcontext.get()));
         d->m_renderControl->initialize();
-#endif
         d->m_glcontext->doneCurrent();
 
         // On Wayland, contexts are implicitly shared and QOpenGLContext::globalShareContext() is null.
@@ -201,14 +185,7 @@ OffscreenQuickView::OffscreenQuickView(QObject *parent, QWindow *renderWindow, E
     connect(d->m_renderControl.get(), &QQuickRenderControl::renderRequested, this, &OffscreenQuickView::handleRenderRequested);
     connect(d->m_renderControl.get(), &QQuickRenderControl::sceneChanged, this, &OffscreenQuickView::handleSceneChanged);
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    d->touchDevice = new QTouchDevice{};
-    d->touchDevice->setCapabilities(QTouchDevice::Position);
-    d->touchDevice->setType(QTouchDevice::TouchScreen);
-    d->touchDevice->setMaximumTouchPoints(10);
-#else
     d->touchDevice = new QPointingDevice({}, {}, QInputDevice::DeviceType::TouchScreen, {}, QInputDevice::Capability::Position, 10, {});
-#endif
 }
 
 OffscreenQuickView::~OffscreenQuickView()
@@ -283,37 +260,21 @@ void OffscreenQuickView::update()
                 return;
             }
         }
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        d->m_view->setRenderTarget(d->m_fbo.get());
-#else
         d->m_view->setRenderTarget(QQuickRenderTarget::fromOpenGLTexture(d->m_fbo->texture(), d->m_fbo->size()));
-#endif
     }
 
     d->m_renderControl->polishItems();
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     d->m_renderControl->beginFrame();
-#endif
     d->m_renderControl->sync();
     d->m_renderControl->render();
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     d->m_renderControl->endFrame();
-#endif
 
     if (usingGl) {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        d->m_view->resetOpenGLState();
-#else
         QQuickOpenGLUtils::resetOpenGLState();
-#endif
     }
 
     if (d->m_useBlit) {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        d->m_image = d->m_renderControl->grab();
-#else
         d->m_image = d->m_view->grabWindow();
-#endif
     }
 
     if (usingGl) {
@@ -389,11 +350,7 @@ bool OffscreenQuickView::forwardTouchDown(qint32 id, const QPointF &pos, std::ch
 {
     d->updateTouchState(Qt::TouchPointPressed, id, pos);
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QTouchEvent event(QEvent::TouchBegin, d->touchDevice, Qt::NoModifier, d->touchState, d->touchPoints);
-#else
     QTouchEvent event(QEvent::TouchBegin, d->touchDevice, Qt::NoModifier, d->touchPoints);
-#endif
     event.setTimestamp(std::chrono::duration_cast<std::chrono::milliseconds>(time).count());
     QCoreApplication::sendEvent(d->m_view.get(), &event);
 
@@ -404,11 +361,7 @@ bool OffscreenQuickView::forwardTouchMotion(qint32 id, const QPointF &pos, std::
 {
     d->updateTouchState(Qt::TouchPointMoved, id, pos);
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QTouchEvent event(QEvent::TouchUpdate, d->touchDevice, Qt::NoModifier, d->touchState, d->touchPoints);
-#else
     QTouchEvent event(QEvent::TouchUpdate, d->touchDevice, Qt::NoModifier, d->touchPoints);
-#endif
     event.setTimestamp(std::chrono::duration_cast<std::chrono::milliseconds>(time).count());
     QCoreApplication::sendEvent(d->m_view.get(), &event);
 
@@ -419,11 +372,7 @@ bool OffscreenQuickView::forwardTouchUp(qint32 id, std::chrono::microseconds tim
 {
     d->updateTouchState(Qt::TouchPointReleased, id, QPointF{});
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QTouchEvent event(QEvent::TouchEnd, d->touchDevice, Qt::NoModifier, d->touchState, d->touchPoints);
-#else
     QTouchEvent event(QEvent::TouchEnd, d->touchDevice, Qt::NoModifier, d->touchPoints);
-#endif
     event.setTimestamp(std::chrono::duration_cast<std::chrono::milliseconds>(time).count());
     QCoreApplication::sendEvent(d->m_view.get(), &event);
 
@@ -543,11 +492,7 @@ void OffscreenQuickView::Private::updateTouchState(Qt::TouchPointState state, qi
                           if (point.state() == Qt::TouchPointReleased) {
                               return true;
                           }
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-                          point.setState(Qt::TouchPointStationary);
-#else
                           QMutableEventPoint::setState(point, QEventPoint::Stationary);
-#endif
                           return false;
                       }),
                       touchPoints.end());
@@ -571,19 +516,11 @@ void OffscreenQuickView::Private::updateTouchState(Qt::TouchPointState state, qi
         }
 
         QTouchEvent::TouchPoint point;
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        point.setState(Qt::TouchPointPressed);
-        point.setId(id + idOffset);
-        point.setScreenPos(pos);
-        point.setScenePos(m_view->mapFromGlobal(pos.toPoint()));
-        point.setPos(m_view->mapFromGlobal(pos.toPoint()));
-#else
         QMutableEventPoint::setState(point, QEventPoint::Pressed);
         QMutableEventPoint::setId(point, id + idOffset);
         QMutableEventPoint::setGlobalPosition(point, pos);
         QMutableEventPoint::setScenePosition(point, m_view->mapFromGlobal(pos.toPoint()));
         QMutableEventPoint::setPosition(point, m_view->mapFromGlobal(pos.toPoint()));
-#endif
 
         touchPoints.append(point);
     } break;
@@ -593,21 +530,11 @@ void OffscreenQuickView::Private::updateTouchState(Qt::TouchPointState state, qi
         }
 
         auto &point = *changed;
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        point.setLastPos(point.pos());
-        point.setLastScenePos(point.scenePos());
-        point.setLastScreenPos(point.screenPos());
-        point.setState(Qt::TouchPointMoved);
-        point.setScenePos(m_view->mapFromGlobal(pos.toPoint()));
-        point.setPos(m_view->mapFromGlobal(pos.toPoint()));
-        point.setScreenPos(pos);
-#else
         QMutableEventPoint::setGlobalLastPosition(point, point.globalPosition());
         QMutableEventPoint::setState(point, QEventPoint::Updated);
         QMutableEventPoint::setScenePosition(point, m_view->mapFromGlobal(pos.toPoint()));
         QMutableEventPoint::setPosition(point, m_view->mapFromGlobal(pos.toPoint()));
         QMutableEventPoint::setGlobalPosition(point, pos);
-#endif
     } break;
     case Qt::TouchPointReleased: {
         if (changed == touchPoints.end()) {
@@ -615,26 +542,12 @@ void OffscreenQuickView::Private::updateTouchState(Qt::TouchPointState state, qi
         }
 
         auto &point = *changed;
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        point.setLastPos(point.pos());
-        point.setLastScreenPos(point.screenPos());
-        point.setState(Qt::TouchPointReleased);
-#else
         QMutableEventPoint::setGlobalLastPosition(point, point.globalPosition());
         QMutableEventPoint::setState(point, QEventPoint::Released);
-#endif
     } break;
     default:
         break;
     }
-
-    // The touch state value is used in QTouchEvent and includes all the states
-    // that the current touch points are in.
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    touchState = std::accumulate(touchPoints.begin(), touchPoints.end(), Qt::TouchPointStates{}, [](auto init, const auto &point) {
-        return init | point.state();
-    });
-#endif
 }
 
 OffscreenQuickScene::OffscreenQuickScene(QObject *parent)
diff --git a/src/main.cpp b/src/main.cpp
index cece92c3b7..4960302389 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -48,12 +48,7 @@
 #include <QStandardPaths>
 #include <QTranslator>
 #include <qplatformdefs.h>
-
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 #include <cerrno>
 
@@ -596,11 +591,7 @@ void Application::updateX11Time(xcb_generic_event_t *event)
     setX11Time(time);
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-bool XcbEventFilter::nativeEventFilter(const QByteArray &eventType, void *message, long int *result)
-#else
 bool XcbEventFilter::nativeEventFilter(const QByteArray &eventType, void *message, qintptr *result)
-#endif
 {
     if (eventType == "xcb_generic_event_t") {
         return kwinApp()->dispatchEvent(static_cast<xcb_generic_event_t *>(message));
diff --git a/src/main.h b/src/main.h
index 5d36810d61..c0b03c6e36 100644
--- a/src/main.h
+++ b/src/main.h
@@ -46,11 +46,7 @@ class Window;
 class XcbEventFilter : public QAbstractNativeEventFilter
 {
 public:
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    bool nativeEventFilter(const QByteArray &eventType, void *message, long int *result) override;
-#else
     bool nativeEventFilter(const QByteArray &eventType, void *message, qintptr *result) override;
-#endif
 };
 
 class X11EventFilterContainer : public QObject
diff --git a/src/main_x11.cpp b/src/main_x11.cpp
index 42442f032d..74b162cbec 100644
--- a/src/main_x11.cpp
+++ b/src/main_x11.cpp
@@ -40,11 +40,7 @@
 #include <QSurfaceFormat>
 #include <QVBoxLayout>
 #include <qplatformdefs.h>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 #include <QtDBus>
 
 // system
diff --git a/src/plugins/kdecorations/aurorae/src/aurorae.cpp b/src/plugins/kdecorations/aurorae/src/aurorae.cpp
index f504e098eb..e5c4f296e0 100644
--- a/src/plugins/kdecorations/aurorae/src/aurorae.cpp
+++ b/src/plugins/kdecorations/aurorae/src/aurorae.cpp
@@ -769,14 +769,6 @@ void ConfigurationModule::initQml()
     }
 
     KPluginMetaData metaData(packageRoot + QLatin1String("/metadata.json"));
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    if (!metaData.isValid()) {
-        metaData = KPluginMetaData::fromDesktopFile(packageRoot + QLatin1String("/metadata.desktop"));
-        if (metaData.isValid()) {
-            qWarning("metadata.desktop format is obsolete. Please convert %s to JSON metadata", qPrintable(metaData.fileName()));
-        }
-    }
-#endif
     if (!metaData.isValid()) {
         return;
     }
diff --git a/src/plugins/qpa/CMakeLists.txt b/src/plugins/qpa/CMakeLists.txt
index 3655e587b0..60672a8c9a 100644
--- a/src/plugins/qpa/CMakeLists.txt
+++ b/src/plugins/qpa/CMakeLists.txt
@@ -28,11 +28,3 @@ target_link_libraries(KWinQpaPlugin PRIVATE
     Fontconfig::Fontconfig
     kwin
 )
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(KWinQpaPlugin PRIVATE
-        Qt::FontDatabaseSupportPrivate
-        Qt::ThemeSupportPrivate
-        Qt::EventDispatcherSupportPrivate
-        Qt::ServiceSupportPrivate
-    )
-endif()
diff --git a/src/plugins/qpa/integration.cpp b/src/plugins/qpa/integration.cpp
index 97bfb0b8c4..76db7e5838 100644
--- a/src/plugins/qpa/integration.cpp
+++ b/src/plugins/qpa/integration.cpp
@@ -28,16 +28,10 @@
 #include <qpa/qplatformwindow.h>
 #include <qpa/qwindowsysteminterface.h>
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtEventDispatcherSupport/private/qunixeventdispatcher_qpa_p.h>
-#include <QtFontDatabaseSupport/private/qgenericunixfontdatabase_p.h>
-#include <QtThemeSupport/private/qgenericunixthemes_p.h>
-#else
 #include <QtGui/private/qgenericunixeventdispatcher_p.h>
 #include <QtGui/private/qgenericunixfontdatabase_p.h>
 #include <QtGui/private/qgenericunixthemes_p.h>
 #include <QtGui/private/qunixeventdispatcher_qpa_p.h>
-#endif
 
 namespace KWin
 {
diff --git a/src/plugins/qpa/integration.h b/src/plugins/qpa/integration.h
index c9981e052c..249f55216f 100644
--- a/src/plugins/qpa/integration.h
+++ b/src/plugins/qpa/integration.h
@@ -12,11 +12,7 @@
 #include <epoxy/egl.h>
 
 #include <QObject>
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtServiceSupport/private/qgenericunixservices_p.h>
-#else
 #include <QtGui/private/qgenericunixservices_p.h>
-#endif
 #include <qpa/qplatformintegration.h>
 
 namespace KWin
diff --git a/src/scripting/genericscriptedconfig.cpp b/src/scripting/genericscriptedconfig.cpp
index 41711f28f9..8aa7d1d3bf 100644
--- a/src/scripting/genericscriptedconfig.cpp
+++ b/src/scripting/genericscriptedconfig.cpp
@@ -71,14 +71,6 @@ void GenericScriptedConfig::createUi()
     }
 
     KPluginMetaData metaData(packageRoot + QLatin1String("/metadata.json"));
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    if (!metaData.isValid()) {
-        metaData = KPluginMetaData::fromDesktopFile(packageRoot + QLatin1String("/metadata.desktop"));
-        if (metaData.isValid()) {
-            qWarning("metadata.desktop format is obsolete. Please convert %s to JSON metadata", qPrintable(metaData.fileName()));
-        }
-    }
-#endif
     if (!metaData.isValid()) {
         layout->addWidget(new QLabel(i18nc("Required file does not exist", "%1 does not contain a valid metadata.json file", qPrintable(packageRoot))));
         return;
diff --git a/src/scripting/scripting.cpp b/src/scripting/scripting.cpp
index 139bb988c1..3b2f6ec39e 100644
--- a/src/scripting/scripting.cpp
+++ b/src/scripting/scripting.cpp
@@ -170,11 +170,7 @@ void KWin::Script::run()
     m_starting = true;
     QFutureWatcher<QByteArray> *watcher = new QFutureWatcher<QByteArray>(this);
     connect(watcher, &QFutureWatcherBase::finished, this, &Script::slotScriptLoadedFromFile);
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    watcher->setFuture(QtConcurrent::run(this, &KWin::Script::loadScriptFromFile, fileName()));
-#else
     watcher->setFuture(QtConcurrent::run(&KWin::Script::loadScriptFromFile, this, fileName()));
-#endif
 }
 
 QByteArray KWin::Script::loadScriptFromFile(const QString &fileName)
diff --git a/src/scripting/windowthumbnailitem.cpp b/src/scripting/windowthumbnailitem.cpp
index bc8e571ed2..ac25e4ab05 100644
--- a/src/scripting/windowthumbnailitem.cpp
+++ b/src/scripting/windowthumbnailitem.cpp
@@ -58,16 +58,9 @@ void ThumbnailTextureProvider::setTexture(const std::shared_ptr<GLTexture> &nati
     if (m_nativeTexture != nativeTexture) {
         const GLuint textureId = nativeTexture->texture();
         m_nativeTexture = nativeTexture;
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        m_texture.reset(m_window->createTextureFromNativeObject(QQuickWindow::NativeObjectTexture,
-                                                                &textureId, 0,
-                                                                nativeTexture->size(),
-                                                                QQuickWindow::TextureHasAlphaChannel));
-#else
         m_texture.reset(QNativeInterface::QSGOpenGLTexture::fromNative(textureId, m_window,
                                                                        nativeTexture->size(),
                                                                        QQuickWindow::TextureHasAlphaChannel));
-#endif
         m_texture->setFiltering(QSGTexture::Linear);
         m_texture->setHorizontalWrapMode(QSGTexture::ClampToEdge);
         m_texture->setVerticalWrapMode(QSGTexture::ClampToEdge);
diff --git a/src/scripting/workspace_wrapper.cpp b/src/scripting/workspace_wrapper.cpp
index 4362d831cf..74e862019c 100644
--- a/src/scripting/workspace_wrapper.cpp
+++ b/src/scripting/workspace_wrapper.cpp
@@ -377,20 +377,12 @@ QQmlListProperty<KWin::Window> DeclarativeScriptWorkspaceWrapper::clients()
     return QQmlListProperty<KWin::Window>(this, nullptr, &DeclarativeScriptWorkspaceWrapper::countClientList, &DeclarativeScriptWorkspaceWrapper::atClientList);
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-int DeclarativeScriptWorkspaceWrapper::countClientList(QQmlListProperty<KWin::Window> *clients)
-#else
 qsizetype DeclarativeScriptWorkspaceWrapper::countClientList(QQmlListProperty<KWin::Window> *clients)
-#endif
 {
     return workspace()->allClientList().size();
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-KWin::Window *DeclarativeScriptWorkspaceWrapper::atClientList(QQmlListProperty<KWin::Window> *clients, int index)
-#else
 KWin::Window *DeclarativeScriptWorkspaceWrapper::atClientList(QQmlListProperty<KWin::Window> *clients, qsizetype index)
-#endif
 {
     return workspace()->allClientList().at(index);
 }
diff --git a/src/scripting/workspace_wrapper.h b/src/scripting/workspace_wrapper.h
index 20aa030686..4606eaccb7 100644
--- a/src/scripting/workspace_wrapper.h
+++ b/src/scripting/workspace_wrapper.h
@@ -353,13 +353,8 @@ class DeclarativeScriptWorkspaceWrapper : public WorkspaceWrapper
     Q_PROPERTY(QQmlListProperty<KWin::Window> clients READ clients)
 public:
     QQmlListProperty<KWin::Window> clients();
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    static int countClientList(QQmlListProperty<KWin::Window> *clients);
-    static KWin::Window *atClientList(QQmlListProperty<KWin::Window> *clients, int index);
-#else
     static qsizetype countClientList(QQmlListProperty<KWin::Window> *clients);
     static KWin::Window *atClientList(QQmlListProperty<KWin::Window> *clients, qsizetype index);
-#endif
 
     explicit DeclarativeScriptWorkspaceWrapper(QObject *parent = nullptr);
 };
diff --git a/src/tablet_input.cpp b/src/tablet_input.cpp
index 55aaf2b4cb..e29da56eee 100644
--- a/src/tablet_input.cpp
+++ b/src/tablet_input.cpp
@@ -74,7 +74,6 @@ void TabletInputRedirection::tabletToolEvent(KWin::InputRedirection::TabletEvent
 
     const auto button = m_tipDown ? Qt::LeftButton : Qt::NoButton;
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     // TODO: Not correct, but it should work fine. In long term, we need to stop using QTabletEvent.
     const QPointingDevice *dev = QPointingDevice::primaryPointingDevice();
     TabletEvent ev(t, dev, pos, pos, pressure,
@@ -83,14 +82,6 @@ void TabletInputRedirection::tabletToolEvent(KWin::InputRedirection::TabletEvent
                    rotation,
                    0, // z
                    Qt::NoModifier, button, button, tabletToolId);
-#else
-    TabletEvent ev(t, pos, pos, QTabletEvent::Stylus, QTabletEvent::Pen, pressure,
-                   xTilt, yTilt,
-                   0, // tangentialPressure
-                   rotation,
-                   0, // z
-                   Qt::NoModifier, tabletToolId.m_uniqueId, button, button, tabletToolId);
-#endif
 
     ev.setTimestamp(std::chrono::duration_cast<std::chrono::milliseconds>(time).count());
     input()->processSpies(std::bind(&InputEventSpy::tabletToolEvent, std::placeholders::_1, &ev));
diff --git a/src/tiles/tile.cpp b/src/tiles/tile.cpp
index 8ab0520e4a..6082770e1b 100644
--- a/src/tiles/tile.cpp
+++ b/src/tiles/tile.cpp
@@ -304,11 +304,7 @@ void Tile::insertChild(int position, Tile *item)
     const bool wasEmpty = m_children.isEmpty();
     item->setParent(this);
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    m_children.insert(std::clamp(position, 0, m_children.length()), item);
-#else
     m_children.insert(std::clamp<qsizetype>(position, 0, m_children.length()), item);
-#endif
 
     if (wasEmpty) {
         Q_EMIT isLayoutChanged(true);
diff --git a/src/useractions.cpp b/src/useractions.cpp
index 4f59e4d7cf..2e618d2c67 100644
--- a/src/useractions.cpp
+++ b/src/useractions.cpp
@@ -845,20 +845,11 @@ void ShortcutDialog::accept()
 {
     QKeySequence seq = shortcut();
     if (!seq.isEmpty()) {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        if (seq[0] == Qt::Key_Escape) {
-#else
         if (seq[0] == QKeyCombination(Qt::Key_Escape)) {
-#endif
             reject();
             return;
         }
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        if (seq[0] == Qt::Key_Space
-            || (seq[0] & Qt::KeyboardModifierMask) == 0) {
-#else
         if (seq[0] == QKeyCombination(Qt::Key_Space) || seq[0].keyboardModifiers() == Qt::NoModifier) {
-#endif
             // clear
             m_ui.keySequenceEdit->clear();
             QDialog::accept();
diff --git a/src/wayland/autotests/client/CMakeLists.txt b/src/wayland/autotests/client/CMakeLists.txt
index 63c6a98193..f92207bad8 100644
--- a/src/wayland/autotests/client/CMakeLists.txt
+++ b/src/wayland/autotests/client/CMakeLists.txt
@@ -29,15 +29,8 @@ add_executable(testWaylandSeat)
 set( testWaylandSeat_SRCS
         test_wayland_seat.cpp
     )
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(testWaylandSeat_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/pointer-gestures/pointer-gestures-unstable-v1.xml
-        BASENAME pointer-gestures-unstable-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testWaylandSeat FILES
-        ${WaylandProtocols_DATADIR}/unstable/pointer-gestures/pointer-gestures-unstable-v1.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testWaylandSeat FILES
+    ${WaylandProtocols_DATADIR}/unstable/pointer-gestures/pointer-gestures-unstable-v1.xml)
 target_sources(testWaylandSeat PRIVATE ${testWaylandSeat_SRCS})
 target_link_libraries( testWaylandSeat Qt::Test Qt::Gui KF6::WaylandClient kwin Wayland::Client Wayland::Server)
 add_test(NAME kwayland-testWaylandSeat COMMAND testWaylandSeat)
diff --git a/src/wayland/autotests/server/CMakeLists.txt b/src/wayland/autotests/server/CMakeLists.txt
index 8ee75df271..52a73210f4 100644
--- a/src/wayland/autotests/server/CMakeLists.txt
+++ b/src/wayland/autotests/server/CMakeLists.txt
@@ -32,15 +32,8 @@ ecm_mark_as_test(testNoXdgRuntimeDir)
 # Test Tablet Interface
 ########################################################
 add_executable(testTabletInterface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(TABLET_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/tablet/tablet-unstable-v2.xml
-        BASENAME tablet-unstable-v2
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testTabletInterface FILES
-        ${WaylandProtocols_DATADIR}/unstable/tablet/tablet-unstable-v2.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testTabletInterface FILES
+    ${WaylandProtocols_DATADIR}/unstable/tablet/tablet-unstable-v2.xml)
 target_sources(testTabletInterface PRIVATE test_tablet_interface.cpp ${TABLET_SRCS})
 target_link_libraries( testTabletInterface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testTabletInterface COMMAND testTabletInterface)
@@ -50,15 +43,8 @@ ecm_mark_as_test(testTabletInterface)
 # Test DataControlInterface
 ########################################################
 add_executable(testDataControlInterface test_datacontrol_interface.cpp ${DATACONTROL_SRCS})
-if (QT_MAJOR_VERSION EQUAL "5")
-ecm_add_qtwayland_client_protocol(DATACONTROL_SRCS
-    PROTOCOL  ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-data-control-unstable-v1.xml
-    BASENAME wlr-data-control-unstable-v1
-)
-else()
-    qt6_generate_wayland_protocol_client_sources(testDataControlInterface FILES
-        ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-data-control-unstable-v1.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testDataControlInterface FILES
+    ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-data-control-unstable-v1.xml)
 target_sources(testDataControlInterface PRIVATE test_datacontrol_interface.cpp ${DATACONTROL_SRCS})
 target_link_libraries( testDataControlInterface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testDataControlInterface COMMAND testDataControlInterface)
@@ -68,15 +54,8 @@ ecm_mark_as_test(testDataControlInterface)
 # Test Keyboard Shortcuts Inhibitor Interface
 ########################################################
 add_executable(testKeyboardShortcutsInhibitorInterface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(KEYBOARD_SHORTCUTS_INHIBITOR_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/keyboard-shortcuts-inhibit/keyboard-shortcuts-inhibit-unstable-v1.xml
-        BASENAME keyboard-shortcuts-inhibit-unstable-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testKeyboardShortcutsInhibitorInterface FILES
-        ${WaylandProtocols_DATADIR}/unstable/keyboard-shortcuts-inhibit/keyboard-shortcuts-inhibit-unstable-v1.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testKeyboardShortcutsInhibitorInterface FILES
+    ${WaylandProtocols_DATADIR}/unstable/keyboard-shortcuts-inhibit/keyboard-shortcuts-inhibit-unstable-v1.xml)
 target_sources(testKeyboardShortcutsInhibitorInterface PRIVATE test_keyboard_shortcuts_inhibitor_interface.cpp ${KEYBOARD_SHORTCUTS_INHIBITOR_SRCS})
 target_link_libraries(testKeyboardShortcutsInhibitorInterface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testKeyboardShortcutsInhibitorInterface COMMAND testKeyboardShortcutsInhibitorInterface)
@@ -86,15 +65,8 @@ ecm_mark_as_test(testKeyboardShortcutsInhibitorInterface)
 # Test Viewporter Interface
 ########################################################
 add_executable(testViewporterInterface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(VIEWPORTER_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/stable/viewporter/viewporter.xml
-        BASENAME viewporter
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testViewporterInterface FILES
-        ${WaylandProtocols_DATADIR}/stable/viewporter/viewporter.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testViewporterInterface FILES
+    ${WaylandProtocols_DATADIR}/stable/viewporter/viewporter.xml)
 target_sources(testViewporterInterface PRIVATE test_viewporter_interface.cpp ${VIEWPORTER_SRCS})
 target_link_libraries(testViewporterInterface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testViewporterInterface COMMAND testViewporterInterface)
@@ -104,15 +76,8 @@ ecm_mark_as_test(testViewporterInterface)
 # Test ScreencastV1Interface
 ########################################################
 add_executable(testScreencastV1Interface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(SCREENCAST_SRCS
-        PROTOCOL PROTOCOL ${PLASMA_WAYLAND_PROTOCOLS_DIR}/zkde-screencast-unstable-v1.xml
-        BASENAME zkde-screencast-unstable-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testScreencastV1Interface FILES
-        ${PLASMA_WAYLAND_PROTOCOLS_DIR}/zkde-screencast-unstable-v1.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testScreencastV1Interface FILES
+    ${PLASMA_WAYLAND_PROTOCOLS_DIR}/zkde-screencast-unstable-v1.xml)
 target_sources(testScreencastV1Interface PRIVATE test_screencast.cpp ${SCREENCAST_SRCS})
 target_link_libraries(testScreencastV1Interface Qt::Test kwin Wayland::Client KF6::WaylandClient)
 add_test(NAME kwayland-testScreencastV1Interface COMMAND testScreencastV1Interface)
@@ -122,18 +87,11 @@ ecm_mark_as_test(testScreencastV1Interface)
 # Test InputMethod Interface
 ########################################################
 add_executable(testInputMethodInterface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(INPUTMETHOD_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
-        BASENAME input-method-unstable-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testInputMethodInterface
-        NO_INCLUDE_CORE_ONLY
-        FILES
-            ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
-    )
-endif()
+qt6_generate_wayland_protocol_client_sources(testInputMethodInterface
+    NO_INCLUDE_CORE_ONLY
+    FILES
+        ${WaylandProtocols_DATADIR}/unstable/input-method/input-method-unstable-v1.xml
+)
 target_sources(testInputMethodInterface PRIVATE test_inputmethod_interface.cpp ../../tests/fakeoutput.cpp ${INPUTMETHOD_SRCS})
 target_link_libraries(testInputMethodInterface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testInputMethodInterface COMMAND testInputMethodInterface)
@@ -143,21 +101,10 @@ ecm_mark_as_test(testInputMethodInterface)
 # Test LayerShellV1 Interface
 ########################################################
 add_executable(testLayerShellV1Interface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(LAYERSHELLV1_SRCS
-        PROTOCOL ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-layer-shell-unstable-v1.xml
-        BASENAME wlr-layer-shell-unstable-v1
-    )
-    ecm_add_qtwayland_client_protocol(LAYERSHELLV1_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
-        BASENAME xdg-shell
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testLayerShellV1Interface FILES
-        ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-layer-shell-unstable-v1.xml
-        ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
-    )
-endif()
+qt6_generate_wayland_protocol_client_sources(testLayerShellV1Interface FILES
+    ${PROJECT_SOURCE_DIR}/src/wayland/protocols/wlr-layer-shell-unstable-v1.xml
+    ${WaylandProtocols_DATADIR}/stable/xdg-shell/xdg-shell.xml
+)
 target_sources(testLayerShellV1Interface PRIVATE test_layershellv1_interface.cpp ${LAYERSHELLV1_SRCS})
 target_link_libraries(testLayerShellV1Interface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testLayerShellV1Interface COMMAND testLayerShellV1Interface)
@@ -168,15 +115,8 @@ ecm_mark_as_test(testLayerShellV1Interface)
 # Test TextInputV3 Interface
 ########################################################
 add_executable(testTextInputV3Interface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(TEXTINPUTV3_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml
-        BASENAME text-input-unstable-v3
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testTextInputV3Interface FILES
-        ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testTextInputV3Interface FILES
+    ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v3.xml)
 target_sources(testTextInputV3Interface PRIVATE test_textinputv3_interface.cpp ${TEXTINPUTV3_SRCS})
 target_link_libraries(testTextInputV3Interface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testTextInputV3Interface COMMAND testTextInputV3Interface)
@@ -186,15 +126,8 @@ ecm_mark_as_test(testTextInputV3Interface)
 # Test TextInputV1 Interface
 ########################################################
 add_executable(testTextInputV1Interface)
-if (QT_MAJOR_VERSION EQUAL "5")
-    ecm_add_qtwayland_client_protocol(TEXTINPUTV1_SRCS
-        PROTOCOL ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v1.xml
-        BASENAME text-input-unstable-v1
-    )
-else()
-    qt6_generate_wayland_protocol_client_sources(testTextInputV1Interface FILES
-        ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v1.xml)
-endif()
+qt6_generate_wayland_protocol_client_sources(testTextInputV1Interface FILES
+    ${WaylandProtocols_DATADIR}/unstable/text-input/text-input-unstable-v1.xml)
 target_sources(testTextInputV1Interface PRIVATE test_textinputv1_interface.cpp ${TEXTINPUTV1_SRCS})
 target_link_libraries(testTextInputV1Interface Qt::Test kwin KF6::WaylandClient Wayland::Client)
 add_test(NAME kwayland-testTextInputV1Interface COMMAND testTextInputV1Interface)
diff --git a/src/workspace.cpp b/src/workspace.cpp
index 17585a1de2..8c07ff8dc3 100644
--- a/src/workspace.cpp
+++ b/src/workspace.cpp
@@ -132,11 +132,7 @@ Workspace::Workspace()
     , m_placementTracker(std::make_unique<PlacementTracker>(this))
 {
     // If KWin was already running it saved its configuration after loosing the selection -> Reread
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    QFuture<void> reparseConfigFuture = QtConcurrent::run(options, &Options::reparseConfiguration);
-#else
     QFuture<void> reparseConfigFuture = QtConcurrent::run(&Options::reparseConfiguration, options);
-#endif
 
     _self = this;
 
diff --git a/src/xkb.cpp b/src/xkb.cpp
index 0dc89082ac..229909363d 100644
--- a/src/xkb.cpp
+++ b/src/xkb.cpp
@@ -17,11 +17,7 @@
 // Qt
 #include <QKeyEvent>
 #include <QTemporaryFile>
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-#include <QtXkbCommonSupport/private/qxkbcommon_p.h>
-#else
 #include <QtGui/private/qxkbcommon_p.h>
-#endif
 // xkbcommon
 #include <xkbcommon/xkbcommon-compose.h>
 #include <xkbcommon/xkbcommon-keysyms.h>
@@ -576,11 +572,6 @@ Qt::Key Xkb::toQtKey(xkb_keysym_t keySym,
     } else if (qtKey > 0xff && keySym <= 0xff) {
         // XKB_KEY_mu, XKB_KEY_ydiaeresis go here
         qtKey = Qt::Key(keySym);
-#if QT_VERSION_MAJOR < 6 // since Qt 5 LTS is frozen
-    } else if (keySym == XKB_KEY_Sys_Req) {
-        // fixed in QTBUG-92087
-        qtKey = Qt::Key_SysReq;
-#endif
     }
     return qtKey;
 }
diff --git a/src/xwayland/databridge.cpp b/src/xwayland/databridge.cpp
index ad38e2d8de..b0de4aea99 100644
--- a/src/xwayland/databridge.cpp
+++ b/src/xwayland/databridge.cpp
@@ -42,11 +42,7 @@ void DataBridge::init()
     kwinApp()->installNativeEventFilter(this);
 }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-bool DataBridge::nativeEventFilter(const QByteArray &eventType, void *message, long int *)
-#else
 bool DataBridge::nativeEventFilter(const QByteArray &eventType, void *message, qintptr *)
-#endif
 {
     if (eventType == "xcb_generic_event_t") {
         xcb_generic_event_t *event = static_cast<xcb_generic_event_t *>(message);
diff --git a/src/xwayland/databridge.h b/src/xwayland/databridge.h
index c63f6e2fff..b43636121d 100644
--- a/src/xwayland/databridge.h
+++ b/src/xwayland/databridge.h
@@ -51,11 +51,7 @@ public:
         return m_dnd;
     }
 
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-    bool nativeEventFilter(const QByteArray &eventType, void *message, long int *result) override;
-#else
     bool nativeEventFilter(const QByteArray &eventType, void *message, qintptr *result) override;
-#endif
 
 private:
     void init();
diff --git a/src/xwayland/xwayland.cpp b/src/xwayland/xwayland.cpp
index 7886034de8..cfe79fe4a7 100644
--- a/src/xwayland/xwayland.cpp
+++ b/src/xwayland/xwayland.cpp
@@ -242,11 +242,7 @@ void Xwayland::dispatchEvents(DispatchEventsMode mode)
     auto pollEventFunc = mode == DispatchEventsMode::Poll ? xcb_poll_for_event : xcb_poll_for_queued_event;
 
     while (xcb_generic_event_t *event = pollEventFunc(connection)) {
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        long result = 0;
-#else
         qintptr result = 0;
-#endif
 
         QAbstractEventDispatcher *dispatcher = QCoreApplication::eventDispatcher();
         dispatcher->filterNativeEvent(QByteArrayLiteral("xcb_generic_event_t"), event, &result);
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 0e716663f2..1bcc8f680e 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,7 +1,3 @@
-if (QT_MAJOR_VERSION EQUAL "5")
-    find_package(Qt6 REQUIRED COMPONENTS WaylandClient)
-endif()
-
 if (XCB_ICCCM_FOUND)
     set(normalhintsbasesizetest_SRCS normalhintsbasesizetest.cpp)
     add_executable(normalhintsbasesizetest ${normalhintsbasesizetest_SRCS})
@@ -11,21 +7,11 @@ endif()
 # next target
 set(screenedgeshowtest_SRCS screenedgeshowtest.cpp)
 add_executable(screenedgeshowtest ${screenedgeshowtest_SRCS})
-target_link_libraries(screenedgeshowtest Qt::Widgets KF6::ConfigCore KF6::WindowSystem KF6::WaylandClient ${XCB_XCB_LIBRARY})
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(screenedgeshowtest Qt::X11Extras)
-else()
-    target_link_libraries(screenedgeshowtest Qt::GuiPrivate)
-endif()
+target_link_libraries(screenedgeshowtest Qt::GuiPrivate Qt::Widgets KF6::ConfigCore KF6::WindowSystem KF6::WaylandClient ${XCB_XCB_LIBRARY})
 target_include_directories(screenedgeshowtest PRIVATE ${CMAKE_SOURCE_DIR}/src)
 
 add_executable(x11shadowreader x11shadowreader.cpp)
-target_link_libraries(x11shadowreader XCB::XCB Qt::Widgets KF6::ConfigCore KF6::WindowSystem)
-if (QT_MAJOR_VERSION EQUAL "5")
-    target_link_libraries(x11shadowreader Qt::X11Extras)
-else()
-    target_link_libraries(x11shadowreader Qt::GuiPrivate)
-endif()
+target_link_libraries(x11shadowreader XCB::XCB Qt::GuiPrivate Qt::Widgets KF6::ConfigCore KF6::WindowSystem)
 target_include_directories(x11shadowreader PRIVATE ${CMAKE_SOURCE_DIR}/src)
 
 add_executable(pointerconstraints pointerconstraintstest.cpp)
@@ -41,23 +27,5 @@ target_link_libraries(cursorhotspottest Qt::Widgets)
 
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 
-if (QT_MAJOR_VERSION EQUAL "5")
-    add_executable(xdgactivationtest-qt5 xdgactivationtest-qt5.cpp)
-    target_link_libraries(xdgactivationtest-qt5 Qt::Widgets Qt::WaylandClient Qt::WaylandClientPrivate Wayland::Client)
-    ecm_add_qtwayland_client_protocol(xdgactivationtest-qt5
-        PROTOCOL ${WaylandProtocols_DATADIR}/staging/xdg-activation/xdg-activation-v1.xml
-        BASENAME xdg-activation-v1
-    )
-
-    add_executable(lockscreenoverlaytest lockscreenoverlaytest.cpp)
-    target_link_libraries(lockscreenoverlaytest Qt::Widgets Qt::WaylandClient Qt::WaylandClientPrivate Wayland::Client KF6::WindowSystem)
-    ecm_add_qtwayland_client_protocol(lockscreenoverlaytest
-        PROTOCOL ${PLASMA_WAYLAND_PROTOCOLS_DIR}/kde-lockscreen-overlay-v1.xml
-        BASENAME kde-lockscreen-overlay-v1
-    )
-endif()
-
-if (TARGET Qt6::Gui)
-    add_executable(xdgactivationtest-qt6 xdgactivationtest-qt6.cpp)
-    target_link_libraries(xdgactivationtest-qt6 Qt6::Widgets)
-endif()
+add_executable(xdgactivationtest-qt6 xdgactivationtest-qt6.cpp)
+target_link_libraries(xdgactivationtest-qt6 Qt6::Widgets)
diff --git a/tests/screenedgeshowtest.cpp b/tests/screenedgeshowtest.cpp
index e42dbbf6d7..40ae6e3c27 100644
--- a/tests/screenedgeshowtest.cpp
+++ b/tests/screenedgeshowtest.cpp
@@ -16,11 +16,7 @@
 #include <QToolButton>
 #include <QWidget>
 #include <QWindow>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 #include <KWindowSystem>
 
diff --git a/tests/x11shadowreader.cpp b/tests/x11shadowreader.cpp
index 652b4d6db3..70699f9c60 100644
--- a/tests/x11shadowreader.cpp
+++ b/tests/x11shadowreader.cpp
@@ -12,11 +12,7 @@
 #include <QLabel>
 #include <QVBoxLayout>
 #include <QWidget>
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 #include <private/qtx11extras_p.h>
-#else
-#include <QX11Info>
-#endif
 
 static QVector<uint32_t> readShadow(quint32 windowId)
 {
diff --git a/tests/xdgactivationtest-qt5.cpp b/tests/xdgactivationtest-qt5.cpp
deleted file mode 100644
index f65ce8b7d8..0000000000
--- a/tests/xdgactivationtest-qt5.cpp
+++ /dev/null
@@ -1,90 +0,0 @@
-/*
-    SPDX-FileCopyrightText: 2022 Aleix Pol Gonzalez <aleixpol@kde.org>
-    SPDX-FileCopyrightText: 2022 Ilya Fedin <fedin-ilja2010@ya.ru>
-
-    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
-*/
-
-#include "qwayland-xdg-activation-v1.h"
-#include <QWaylandClientExtensionTemplate>
-#include <QtWidgets>
-#include <qpa/qplatformnativeinterface.h>
-
-class WaylandXdgActivationTokenV1 : public QObject, public QtWayland::xdg_activation_token_v1
-{
-    Q_OBJECT
-public:
-    void xdg_activation_token_v1_done(const QString &token) override
-    {
-        Q_EMIT done(token);
-    }
-
-Q_SIGNALS:
-    void done(const QString &token);
-};
-
-class WaylandXdgActivationV1 : public QWaylandClientExtensionTemplate<WaylandXdgActivationV1>, public QtWayland::xdg_activation_v1
-{
-public:
-    WaylandXdgActivationV1()
-        : QWaylandClientExtensionTemplate<WaylandXdgActivationV1>(1)
-    {
-        // QWaylandClientExtensionTemplate invokes this with a QueuedConnection but we want shortcuts
-        // to be inhibited immediately.
-        QMetaObject::invokeMethod(this, "addRegistryListener");
-    }
-
-    WaylandXdgActivationTokenV1 *requestXdgActivationToken(wl_seat *seat, struct ::wl_surface *surface, uint32_t serial, const QString &app_id)
-    {
-        auto wl = get_activation_token();
-        auto provider = new WaylandXdgActivationTokenV1;
-        provider->init(wl);
-        if (surface) {
-            provider->set_surface(surface);
-        }
-
-        if (!app_id.isEmpty()) {
-            provider->set_app_id(app_id);
-        }
-
-        if (seat) {
-            provider->set_serial(serial, seat);
-        }
-        provider->commit();
-        return provider;
-    }
-};
-
-int main(int argc, char *argv[])
-{
-
-    QApplication app(argc, argv);
-    QWidget window1(nullptr, Qt::Window);
-    window1.setWindowTitle("Window 1");
-    window1.setLayout(new QVBoxLayout);
-    QPushButton p("Raise the Window 2");
-    window1.layout()->addWidget(&p);
-    window1.show();
-
-    QWidget window2(nullptr, Qt::Window);
-    window2.setWindowTitle("Window 2");
-    window2.show();
-
-    WaylandXdgActivationV1 activation;
-    QObject::connect(&p, &QPushButton::clicked, &app, [&] {
-        QPlatformNativeInterface *native = qGuiApp->platformNativeInterface();
-        auto seat = static_cast<wl_seat *>(native->nativeResourceForIntegration("wl_seat"));
-        wl_surface *surface = reinterpret_cast<wl_surface *>(native->nativeResourceForWindow(QByteArrayLiteral("surface"), window1.windowHandle()));
-        auto req = activation.requestXdgActivationToken(seat, surface, 0, {});
-        QObject::connect(req, &WaylandXdgActivationTokenV1::done, &app, [&activation, &window2](const QString &token) {
-            window2.show();
-            QPlatformNativeInterface *native = qGuiApp->platformNativeInterface();
-            wl_surface *surface = reinterpret_cast<wl_surface *>(native->nativeResourceForWindow(QByteArrayLiteral("surface"), window2.windowHandle()));
-            activation.activate(token, surface);
-        });
-    });
-
-    return app.exec();
-}
-
-#include "xdgactivationtest-qt5.moc"