diff --git a/src/kdbusservice.h b/src/kdbusservice.h
--- a/src/kdbusservice.h
+++ b/src/kdbusservice.h
@@ -115,7 +115,17 @@
          * The exit value of a @c Unique instance can be set from the running
          * instance with setExitValue(), the default value is @c 0.
          */
-        NoExitOnFailure = 4
+        NoExitOnFailure = 4,
+        /**
+         * Indicates that if there's already a unique service running, to be quit and replaced
+         * with our own.
+         *
+         * If exported, it will try first quitting the service calling org.qtproject.Qt.QCoreApplication.quit,
+         * which is exported by @class KDBusService by default.
+         *
+         * @since 5.65
+         */
+        Replace = 8
     };
     Q_ENUM(StartupOption)
 
diff --git a/src/kdbusservice.cpp b/src/kdbusservice.cpp
--- a/src/kdbusservice.cpp
+++ b/src/kdbusservice.cpp
@@ -196,7 +196,14 @@
             return;
         }
 
-        if (options & KDBusService::Unique) {
+        if (options & KDBusService::Replace) {
+            auto message = QDBusMessage::createMethodCall(d->serviceName,
+                                                    QStringLiteral("/MainApplication"),
+                                                    QStringLiteral("org.qtproject.Qt.QCoreApplication"),
+                                                    QStringLiteral("quit"));
+            QDBusConnection::sessionBus().asyncCall(message);
+            waitForRegistration();
+        } else if (options & KDBusService::Unique) {
             // Already running so it's ok!
             QVariantMap platform_data;
             platform_data.insert(QStringLiteral("desktop-startup-id"), QString::fromUtf8(qgetenv("DESKTOP_STARTUP_ID")));