diff --git a/toolkit/xre/MacRunFromDmgUtils.h b/toolkit/xre/MacRunFromDmgUtils.h
index 45b167a0b3ed..d93e6445b1b4 100644
--- a/toolkit/xre/MacRunFromDmgUtils.h
+++ b/toolkit/xre/MacRunFromDmgUtils.h
@@ -9,8 +9,7 @@
 #ifndef MacRunFromDmgUtils_h_
 #define MacRunFromDmgUtils_h_
 
-namespace mozilla {
-namespace MacRunFromDmgUtils {
+namespace mozilla::MacRunFromDmgUtils {
 
 /**
  * Returns true if the app is running from the read-only filesystem of a
@@ -20,16 +19,15 @@ namespace MacRunFromDmgUtils {
 bool IsAppRunningFromDmg();
 
 /**
- * Checks whether the app is running from a read-only .dmg image and, if so,
- * asks the user for permission before attempting to install the app and launch
- * it.
+ * Checks whether the app is running from a read-only .dmg image or a read-only
+ * app translocated location and, if so, asks the user for permission before
+ * attempting to install the app and launch it.
  *
  * Returns true if the app has been installed and relaunched, in which case
  * this instance of the app should exit.
  */
-bool MaybeInstallFromDmgAndRelaunch();
+bool MaybeInstallAndRelaunch();
 
-}  // namespace MacRunFromDmgUtils
-}  // namespace mozilla
+}  // namespace mozilla::MacRunFromDmgUtils
 
 #endif
diff --git a/toolkit/xre/MacRunFromDmgUtils.mm b/toolkit/xre/MacRunFromDmgUtils.mm
index cf96d304e7f2..f25c7a33cb3e 100644
--- a/toolkit/xre/MacRunFromDmgUtils.mm
+++ b/toolkit/xre/MacRunFromDmgUtils.mm
@@ -38,8 +38,7 @@
 // https://developer.apple.com/documentation/iokit
 // https://developer.apple.com/library/archive/documentation/DeviceDrivers/Conceptual/IOKitFundamentals/
 
-namespace mozilla {
-namespace MacRunFromDmgUtils {
+namespace mozilla::MacRunFromDmgUtils {
 
 /**
  * Opens a dialog to ask the user whether the existing app in the Applications
@@ -322,7 +321,7 @@ bool LaunchElevatedDmgInstall(NSString* aBundlePath, NSArray* aArguments) {
 
 // Note: both arguments are expected to contain the app name (to end with
 // '.app').
-static bool InstallFromDmg(NSString* aBundlePath, NSString* aDestPath) {
+static bool InstallFromPath(NSString* aBundlePath, NSString* aDestPath) {
   bool installSuccessful = false;
   NSFileManager* fileManager = [NSFileManager defaultManager];
   if ([fileManager copyItemAtPath:aBundlePath toPath:aDestPath error:nil]) {
@@ -456,15 +455,22 @@ bool IsAppRunningFromDmg() {
   NS_OBJC_END_TRY_BLOCK_RETURN(false);
 }
 
-bool MaybeInstallFromDmgAndRelaunch() {
+bool MaybeInstallAndRelaunch() {
   NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
 
   @autoreleasepool {
     bool isFromDmg = IsAppRunningFromDmg();
+    bool isTranslocated = false;
+    if (!isFromDmg) {
+      NSString* bundlePath = [[NSBundle mainBundle] bundlePath];
+      if ([bundlePath containsString:@"/AppTranslocation/"]) {
+        isTranslocated = true;
+      }
+    }
 
     Telemetry::ScalarSet(Telemetry::ScalarID::STARTUP_IS_RUN_FROM_DMG, isFromDmg);
 
-    if (!isFromDmg) {
+    if (!isFromDmg && !isTranslocated) {
       if (getenv("MOZ_INSTALLED_AND_RELAUNCHED_FROM_DMG")) {
         unsetenv("MOZ_INSTALLED_AND_RELAUNCHED_FROM_DMG");
         glean::startup::run_from_dmg_install_outcome.Get("installed_and_relaunched"_ns).Set(true);
@@ -498,6 +504,7 @@ bool MaybeInstallFromDmgAndRelaunch() {
     // a more sophisticated user intentionally running from .dmg.
     if ([fileManager fileExistsAtPath:destPath]) {
       if (AskUserIfWeShouldLaunchExistingInstall()) {
+        StripQuarantineBit(destPath);
         LaunchInstalledApp(destPath);
         glean::startup::run_from_dmg_install_outcome.Get("user_accepted_launch_existing"_ns)
             .Set(true);
@@ -513,7 +520,7 @@ bool MaybeInstallFromDmgAndRelaunch() {
       return false;
     }
 
-    if (!InstallFromDmg(bundlePath, destPath)) {
+    if (!InstallFromPath(bundlePath, destPath)) {
       ShowInstallFailedDialog();
       return false;
     }
@@ -526,5 +533,4 @@ bool MaybeInstallFromDmgAndRelaunch() {
   NS_OBJC_END_TRY_BLOCK_RETURN(false);
 }
 
-}  // namespace MacRunFromDmgUtils
-}  // namespace mozilla
+}  // namespace mozilla::MacRunFromDmgUtils
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index e239751173f6..b0d3fd3f6ff6 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -5615,9 +5615,9 @@ nsresult XREMain::XRE_mainRun() {
       NS_ENSURE_SUCCESS(rv, NS_ERROR_FAILURE);
 
 #  ifdef MOZILLA_OFFICIAL
-      // Check if we're running from a DMG and allow the user to install to the
-      // Applications directory.
-      if (MacRunFromDmgUtils::MaybeInstallFromDmgAndRelaunch()) {
+      // Check if we're running from a DMG or an app translocated location and
+      // allow the user to install to the Applications directory.
+      if (MacRunFromDmgUtils::MaybeInstallAndRelaunch()) {
         bool userAllowedQuit = true;
         appStartup->Quit(nsIAppStartup::eForceQuit, 0, &userAllowedQuit);
       }