diff --git a/browser/components/shell/Windows11TaskbarPinning.cpp b/browser/components/shell/Windows11TaskbarPinning.cpp
index 31a6af66bf7c..0c6da9a853f4 100644
--- a/browser/components/shell/Windows11TaskbarPinning.cpp
+++ b/browser/components/shell/Windows11TaskbarPinning.cpp
@@ -17,6 +17,7 @@
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WinHeaderOnlyUtils.h"
 #include "mozilla/widget/WinTaskbar.h"
+#include "WinUtils.h"
 
 #include "mozilla/Logging.h"
 
@@ -213,21 +214,27 @@ Win11PinToTaskBarResult PinCurrentAppToTaskbarWin11(
                                     primaryAumid = nsString(primaryAumid)](
                                        Win11PinToTaskBarResultStatus status) {
           // Set AUMID back and ensure the icon is set correctly
-          HRESULT hr =
-              SetCurrentProcessExplicitAppUserModelID(primaryAumid.get());
-          if (FAILED(hr)) {
-            TASKBAR_PINNING_LOG(LogLevel::Debug,
-                                "Taskbar: reverting AUMID after pinning "
-                                "operation failed. HRESULT = 0x%lx",
-                                hr);
+          if (!widget::WinUtils::HasPackageIdentity()) {
+            HRESULT hr =
+                SetCurrentProcessExplicitAppUserModelID(primaryAumid.get());
+            if (FAILED(hr)) {
+              TASKBAR_PINNING_LOG(LogLevel::Debug,
+                                  "Taskbar: reverting AUMID after pinning "
+                                  "operation failed. HRESULT = 0x%lx",
+                                  hr);
+            }
           }
           resultStatus = status;
           event.Set();
         };
 
-        hr = SetCurrentProcessExplicitAppUserModelID(aumid.get());
-        if (FAILED(hr)) {
-          return CompletedOperations(Win11PinToTaskBarResultStatus::Failed);
+        // Set the process to have the AUMID of the shortcut we want to pin,
+        // this is only necessary for Win32 builds
+        if (!widget::WinUtils::HasPackageIdentity()) {
+          hr = SetCurrentProcessExplicitAppUserModelID(aumid.get());
+          if (FAILED(hr)) {
+            return CompletedOperations(Win11PinToTaskBarResultStatus::Failed);
+          }
         }
 
         ComPtr<ITaskbarManager> taskbar;
@@ -264,13 +271,15 @@ Win11PinToTaskBarResult PinCurrentAppToTaskbarWin11(
               [&event, &resultStatus,
                primaryAumid](Win11PinToTaskBarResultStatus status) -> HRESULT {
             // Set AUMID back and ensure the icon is set correctly
-            HRESULT hr =
-                SetCurrentProcessExplicitAppUserModelID(primaryAumid.get());
-            if (FAILED(hr)) {
-              TASKBAR_PINNING_LOG(LogLevel::Debug,
-                                  "Taskbar: reverting AUMID after pinning "
-                                  "operation failed. HRESULT = 0x%lx",
-                                  hr);
+            if (!widget::WinUtils::HasPackageIdentity()) {
+              HRESULT hr =
+                  SetCurrentProcessExplicitAppUserModelID(primaryAumid.get());
+              if (FAILED(hr)) {
+                TASKBAR_PINNING_LOG(LogLevel::Debug,
+                                    "Taskbar: reverting AUMID after pinning "
+                                    "operation failed. HRESULT = 0x%lx",
+                                    hr);
+              }
             }
             resultStatus = status;
             event.Set();
diff --git a/browser/components/shell/nsIWindowsShellService.idl b/browser/components/shell/nsIWindowsShellService.idl
index 37d858b10896..4ec61c6ce061 100644
--- a/browser/components/shell/nsIWindowsShellService.idl
+++ b/browser/components/shell/nsIWindowsShellService.idl
@@ -424,6 +424,16 @@ interface nsIWindowsShellService : nsIShellService
   boolean checkAllProgIDsExist();
   boolean checkBrowserUserChoiceHashes();
 
+  /*
+   * Retrieves the application-defined, explicit Application User Model ID
+   * for the current process. This function is only to be used on
+   * Windows for testing purposes
+   *
+   * @return string AUMID
+   * @throws NS_ERROR_FAILURE when the AUMID cannot be fetched
+   */
+  AString checkCurrentProcessAUMIDForTesting();
+
   /*
    * Determines whether or not Firefox is the "Default Handler", i.e.,
    * is registered to handle, the given file extension (like ".pdf")
diff --git a/browser/components/shell/nsWindowsShellService.cpp b/browser/components/shell/nsWindowsShellService.cpp
index 29126a828735..770bc5d798d2 100644
--- a/browser/components/shell/nsWindowsShellService.cpp
+++ b/browser/components/shell/nsWindowsShellService.cpp
@@ -377,6 +377,29 @@ nsWindowsShellService::CheckBrowserUserChoiceHashes(bool* aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsWindowsShellService::CheckCurrentProcessAUMIDForTesting(
+    nsAString& aRetAumid) {
+  PWSTR id;
+  HRESULT hr;
+
+  // We can't fetch process AUMID for MSIX builds,
+  // since SetCurrentProcessExplicitAppUserModelID
+  // has no effect on it
+  if (widget::WinUtils::HasPackageIdentity()) {
+    aRetAumid.Assign(u"MSIXAumidTestValue"_ns);
+  } else {
+    hr = GetCurrentProcessExplicitAppUserModelID(&id);
+    if (FAILED(hr)) {
+      return NS_ERROR_FAILURE;
+    }
+    aRetAumid.Assign(id);
+    CoTaskMemFree(id);
+  }
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsWindowsShellService::CanSetDefaultBrowserUserChoice(bool* aResult) {
   *aResult = false;
diff --git a/browser/components/shell/test/browser.toml b/browser/components/shell/test/browser.toml
index b699e896a31a..83233efbdbd9 100644
--- a/browser/components/shell/test/browser.toml
+++ b/browser/components/shell/test/browser.toml
@@ -91,6 +91,9 @@ skip-if = [
 run-if = ["os == 'win'"]
 tags = "os_integration"
 
+["browser_processAUMID.js"]
+run-if = ["os == 'win'"]
+
 ["browser_setDefaultBrowser.js"]
 tags = "os_integration"
 
diff --git a/browser/components/shell/test/browser_processAUMID.js b/browser/components/shell/test/browser_processAUMID.js
new file mode 100644
index 000000000000..58d271e75660
--- /dev/null
+++ b/browser/components/shell/test/browser_processAUMID.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * https://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Bug 1950734 tracks how calling PinCurrentAppToTaskbarWin11
+ * on MSIX may cause the process AUMID to be unnecessarily changed.
+ * This test verifies that the behaviour will no longer happen
+ */
+
+ChromeUtils.defineESModuleGetters(this, {
+  ShellService: "resource:///modules/ShellService.sys.mjs",
+});
+
+add_task(async function test_processAUMID() {
+  let processAUMID = ShellService.checkCurrentProcessAUMIDForTesting();
+
+  // This function will trigger the relevant code paths that
+  // incorrectly changes the process AUMID on MSIX, prior to
+  // Bug 1950734 being fixed
+  await ShellService.checkPinCurrentAppToTaskbarAsync(false);
+
+  is(
+    processAUMID,
+    ShellService.checkCurrentProcessAUMIDForTesting(),
+    "The process AUMID should not be changed"
+  );
+});