diff --git a/.changeset/cyan-dingos-watch.md b/.changeset/cyan-dingos-watch.md
new file mode 100644
index 0000000000..7b15d30112
--- /dev/null
+++ b/.changeset/cyan-dingos-watch.md
@@ -0,0 +1,5 @@
+---
+'@backstage/test-utils': patch
+---
+
+Allow `ExternalRouteRef` instances to be passed as a route ref to `mountedRoutes`.
diff --git a/packages/test-utils/src/testUtils/appWrappers.tsx b/packages/test-utils/src/testUtils/appWrappers.tsx
index cc67a5b707..56d6e07805 100644
--- a/packages/test-utils/src/testUtils/appWrappers.tsx
+++ b/packages/test-utils/src/testUtils/appWrappers.tsx
@@ -22,6 +22,7 @@ import privateExports, {
   defaultSystemIcons,
   BootErrorPageProps,
   RouteRef,
+  ExternalRouteRef,
   createPlugin,
   createRoutableExtension,
 } from '@backstage/core-api';
@@ -62,7 +63,7 @@ type TestAppOptions = {
    * // ...
    * const link = useRouteRef(myRouteRef)
    */
-  mountedRoutes?: { [path: string]: RouteRef };
+  mountedRoutes?: { [path: string]: RouteRef | ExternalRouteRef };
 };
 
 /**
diff --git a/plugins/catalog/src/components/CatalogPage/CatalogPage.test.tsx b/plugins/catalog/src/components/CatalogPage/CatalogPage.test.tsx
index 6d4d18e4f2..accfe6eda4 100644
--- a/plugins/catalog/src/components/CatalogPage/CatalogPage.test.tsx
+++ b/plugins/catalog/src/components/CatalogPage/CatalogPage.test.tsx
@@ -33,6 +33,7 @@ import { MockStorageApi, wrapInTestApp } from '@backstage/test-utils';
 import { fireEvent, render, waitFor } from '@testing-library/react';
 import React from 'react';
 import { EntityFilterGroupsProvider } from '../../filter';
+import { createComponentRouteRef } from '../../routes';
 import { CatalogPage } from './CatalogPage';
 
 describe('CatalogPage', () => {
@@ -116,6 +117,11 @@ describe('CatalogPage', () => {
         >
           <EntityFilterGroupsProvider>{children}</EntityFilterGroupsProvider>,
         </ApiProvider>,
+        {
+          mountedRoutes: {
+            '/create': createComponentRouteRef,
+          },
+        },
       ),
     );