diff --git a/.changeset/chatty-coats-sin.md b/.changeset/chatty-coats-sin.md
new file mode 100644
index 0000000000..3842074f4c
--- /dev/null
+++ b/.changeset/chatty-coats-sin.md
@@ -0,0 +1,5 @@
+---
+'@backstage/frontend-defaults': minor
+---
+
+**BREAKING**: Moved `createPublicSignInApp` to the `/alpha` sub-path export.
diff --git a/packages/app-next/src/index-public-experimental.tsx b/packages/app-next/src/index-public-experimental.tsx
index 34198f9553..4c01c428df 100644
--- a/packages/app-next/src/index-public-experimental.tsx
+++ b/packages/app-next/src/index-public-experimental.tsx
@@ -15,7 +15,7 @@
  */
 
 import ReactDOM from 'react-dom/client';
-import { createPublicSignInApp } from '@backstage/frontend-defaults';
+import { createPublicSignInApp } from '@backstage/frontend-defaults/alpha';
 import '@backstage/ui/css/styles.css';
 
 const app = createPublicSignInApp();
diff --git a/packages/frontend-defaults/package.json b/packages/frontend-defaults/package.json
index 5a2cfb6eb3..4bbbf8986d 100644
--- a/packages/frontend-defaults/package.json
+++ b/packages/frontend-defaults/package.json
@@ -5,9 +5,7 @@
     "role": "web-library"
   },
   "publishConfig": {
-    "access": "public",
-    "main": "dist/index.esm.js",
-    "types": "dist/index.d.ts"
+    "access": "public"
   },
   "repository": {
     "type": "git",
@@ -16,8 +14,23 @@
   },
   "license": "Apache-2.0",
   "sideEffects": false,
+  "exports": {
+    ".": "./src/index.ts",
+    "./alpha": "./src/alpha/index.ts",
+    "./package.json": "./package.json"
+  },
   "main": "src/index.ts",
   "types": "src/index.ts",
+  "typesVersions": {
+    "*": {
+      "alpha": [
+        "src/alpha/index.ts"
+      ],
+      "package.json": [
+        "package.json"
+      ]
+    }
+  },
   "files": [
     "dist"
   ],
diff --git a/packages/frontend-defaults/report-alpha.api.md b/packages/frontend-defaults/report-alpha.api.md
new file mode 100644
index 0000000000..1bd66e6521
--- /dev/null
+++ b/packages/frontend-defaults/report-alpha.api.md
@@ -0,0 +1,15 @@
+## API Report File for "@backstage/frontend-defaults"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+import { CreateAppOptions } from '@backstage/frontend-defaults';
+import { JSX as JSX_2 } from 'react';
+
+// @alpha
+export function createPublicSignInApp(options?: CreateAppOptions): {
+  createRoot(): JSX_2.Element;
+};
+
+// (No @packageDocumentation comment for this package)
+```
diff --git a/packages/frontend-defaults/report.api.md b/packages/frontend-defaults/report.api.md
index 37c770074e..ef7ae6a944 100644
--- a/packages/frontend-defaults/report.api.md
+++ b/packages/frontend-defaults/report.api.md
@@ -41,11 +41,6 @@ export interface CreateAppOptions {
   pluginInfoResolver?: FrontendPluginInfoResolver;
 }
 
-// @public
-export function createPublicSignInApp(options?: CreateAppOptions): {
-  createRoot(): JSX_2;
-};
-
 // @public (undocumented)
 export function discoverAvailableFeatures(config: Config): {
   features: (FrontendFeature | FrontendFeatureLoader)[];
diff --git a/packages/frontend-defaults/src/createPublicSignInApp.test.tsx b/packages/frontend-defaults/src/alpha/createPublicSignInApp.test.tsx
similarity index 100%
rename from packages/frontend-defaults/src/createPublicSignInApp.test.tsx
rename to packages/frontend-defaults/src/alpha/createPublicSignInApp.test.tsx
diff --git a/packages/frontend-defaults/src/createPublicSignInApp.tsx b/packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx
similarity index 96%
rename from packages/frontend-defaults/src/createPublicSignInApp.tsx
rename to packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx
index af7107681b..90c6e5e178 100644
--- a/packages/frontend-defaults/src/createPublicSignInApp.tsx
+++ b/packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx
@@ -21,7 +21,8 @@ import {
   useApi,
 } from '@backstage/frontend-plugin-api';
 import { useAsync, useMountEffect } from '@react-hookz/web';
-import { CreateAppOptions, createApp } from './createApp';
+import { createApp } from '../createApp';
+import { CreateAppOptions } from '@backstage/frontend-defaults';
 import appPlugin from '@backstage/plugin-app';
 
 // This is a copy of the CookieAuthRedirect component from the auth-react
@@ -84,7 +85,7 @@ export function InternalCookieAuthRedirect() {
  * });
  * ```
  *
- * @public
+ * @alpha
  */
 export function createPublicSignInApp(options?: CreateAppOptions) {
   return createApp({
diff --git a/packages/frontend-defaults/src/alpha/index.ts b/packages/frontend-defaults/src/alpha/index.ts
new file mode 100644
index 0000000000..f9e45bdeec
--- /dev/null
+++ b/packages/frontend-defaults/src/alpha/index.ts
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2025 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export { createPublicSignInApp } from './createPublicSignInApp';
diff --git a/packages/frontend-defaults/src/index.ts b/packages/frontend-defaults/src/index.ts
index 68d4c72568..0897d9f38e 100644
--- a/packages/frontend-defaults/src/index.ts
+++ b/packages/frontend-defaults/src/index.ts
@@ -21,6 +21,5 @@
  */
 
 export { createApp, type CreateAppOptions } from './createApp';
-export { createPublicSignInApp } from './createPublicSignInApp';
 export { discoverAvailableFeatures } from './discovery';
 export { resolveAsyncFeatures } from './resolution';