diff --git a/.changeset/api-override-test-utils.md b/.changeset/api-override-test-utils.md
index f2c73db7f3..6ea60f9e1b 100644
--- a/.changeset/api-override-test-utils.md
+++ b/.changeset/api-override-test-utils.md
@@ -2,7 +2,7 @@
 '@backstage/frontend-test-utils': patch
 ---
 
-Added an `apis` option to `createExtensionTester` and `renderInTestApp` to override APIs when testing extensions. Use the `mockApis` helpers to create mock implementations:
+Added an `apis` option to `createExtensionTester`, `renderInTestApp`, and `renderTestApp` to override APIs when testing extensions. Use the `mockApis` helpers to create mock implementations:
 
 ```typescript
 import { identityApiRef } from '@backstage/frontend-plugin-api';
@@ -27,4 +27,15 @@ renderInTestApp(<MyComponent />, {
     ],
   ],
 });
+
+// Override APIs in renderTestApp
+renderTestApp({
+  extensions: [myExtension],
+  apis: [
+    [
+      identityApiRef,
+      mockApis.identity({ userEntityRef: 'user:default/guest' }),
+    ],
+  ],
+});
 ```
diff --git a/packages/frontend-test-utils/report.api.md b/packages/frontend-test-utils/report.api.md
index b1cee9ba1a..fa57b76e82 100644
--- a/packages/frontend-test-utils/report.api.md
+++ b/packages/frontend-test-utils/report.api.md
@@ -126,16 +126,17 @@ export function renderInTestApp<TApiPairs extends any[] = any[]>(
 ): RenderResult;
 
 // @public
-export function renderTestApp(
-  options: RenderTestAppOptions,
+export function renderTestApp<TApiPairs extends any[] = any[]>(
+  options: RenderTestAppOptions<TApiPairs>,
 ): RenderResult<testingLibraryDomTypesQueries, HTMLElement, HTMLElement>;
 
 // @public
-export type RenderTestAppOptions = {
+export type RenderTestAppOptions<TApiPairs extends any[] = any[]> = {
   config?: JsonObject;
   extensions?: ExtensionDefinition<any>[];
   features?: FrontendFeature[];
   initialRouteEntries?: string[];
+  apis?: readonly [...TestApiPairs<TApiPairs>];
 };
 
 // @public
diff --git a/packages/frontend-test-utils/src/app/renderTestApp.tsx b/packages/frontend-test-utils/src/app/renderTestApp.tsx
index 879e3fe1ae..b12d3ffd8c 100644
--- a/packages/frontend-test-utils/src/app/renderTestApp.tsx
+++ b/packages/frontend-test-utils/src/app/renderTestApp.tsx
@@ -17,6 +17,7 @@
 import { createSpecializedApp } from '@backstage/frontend-app-api';
 import {
   coreExtensionData,
+  createApiFactory,
   createFrontendModule,
   createFrontendPlugin,
   ExtensionDefinition,
@@ -28,6 +29,9 @@ import { JsonObject } from '@backstage/types';
 import { ConfigReader } from '@backstage/config';
 import { MemoryRouter } from 'react-router-dom';
 import { RouterBlueprint } from '@backstage/plugin-app-react';
+import { type TestApiPairs } from '../utils';
+// eslint-disable-next-line @backstage/no-relative-monorepo-imports
+import type { CreateSpecializedAppInternalOptions } from '../../../frontend-app-api/src/wiring/createSpecializedApp';
 
 const DEFAULT_MOCK_CONFIG = {
   app: { baseUrl: 'http://localhost:3000' },
@@ -39,7 +43,7 @@ const DEFAULT_MOCK_CONFIG = {
  *
  * @public
  */
-export type RenderTestAppOptions = {
+export type RenderTestAppOptions<TApiPairs extends any[] = any[]> = {
   /**
    * Additional configuration passed to the app when rendering elements inside it.
    */
@@ -58,6 +62,23 @@ export type RenderTestAppOptions = {
    * Initial route entries to use for the router.
    */
   initialRouteEntries?: string[];
+
+  /**
+   * API overrides to provide to the test app. Use `mockApis` helpers
+   * from `@backstage/frontend-test-utils` to create mock implementations.
+   *
+   * @example
+   * ```ts
+   * import { identityApiRef } from '@backstage/frontend-plugin-api';
+   * import { mockApis } from '@backstage/frontend-test-utils';
+   *
+   * renderTestApp({
+   *   apis: [[identityApiRef, mockApis.identity({ userEntityRef: 'user:default/guest' })]],
+   *   extensions: [...],
+   * })
+   * ```
+   */
+  apis?: readonly [...TestApiPairs<TApiPairs>];
 };
 
 const appPluginOverride = appPlugin.withOverrides({
@@ -74,7 +95,9 @@ const appPluginOverride = appPlugin.withOverrides({
  *
  * @public
  */
-export function renderTestApp(options: RenderTestAppOptions) {
+export function renderTestApp<TApiPairs extends any[] = any[]>(
+  options: RenderTestAppOptions<TApiPairs>,
+) {
   const extensions = [...(options.extensions ?? [])];
 
   const features: FrontendFeature[] = [
@@ -111,7 +134,12 @@ export function renderTestApp(options: RenderTestAppOptions) {
         data: options?.config ?? DEFAULT_MOCK_CONFIG,
       },
     ]),
-  });
+    __internal: options?.apis && {
+      apiFactoryOverrides: options.apis.map(([apiRef, implementation]) =>
+        createApiFactory(apiRef, implementation),
+      ),
+    },
+  } as CreateSpecializedAppInternalOptions);
 
   return render(
     app.tree.root.instance!.getData(coreExtensionData.reactElement),