diff --git a/.changeset/extension-point-middleware-backend-defaults.md b/.changeset/extension-point-middleware-backend-defaults.md
index 481ba41bed..73add7bc7f 100644
--- a/.changeset/extension-point-middleware-backend-defaults.md
+++ b/.changeset/extension-point-middleware-backend-defaults.md
@@ -2,4 +2,4 @@
 '@backstage/backend-defaults': patch
 ---
 
-Added `extensionPointFactoryMiddleware` option to `createBackend()` to reimplement extension point outputs at backend initialization time. Also re-exports `ExtensionPointFactoryMiddleware` type and `createExtensionPointFactoryMiddleware` helper from `@backstage/backend-app-api`.
+Exported `defaultServiceFactories` to allow use with `createSpecializedBackend` for advanced configuration like `extensionPointFactoryMiddleware`.
diff --git a/packages/backend-app-api/report.api.md b/packages/backend-app-api/report.api.md
index e0557b8fd0..63e8bb1d27 100644
--- a/packages/backend-app-api/report.api.md
+++ b/packages/backend-app-api/report.api.md
@@ -44,10 +44,10 @@ export interface BackendStartupResult {
 }
 
 // @public
-export function createExtensionPointFactoryMiddleware<T>(
-  extensionPoint: ExtensionPoint<T>,
-  middleware: (original: T) => T,
-): ExtensionPointFactoryMiddleware;
+export function createExtensionPointFactoryMiddleware<T>(options: {
+  extensionPoint: ExtensionPoint<T>;
+  middleware: (original: T) => Promise<T>;
+}): ExtensionPointFactoryMiddleware<T>;
 
 // @public (undocumented)
 export function createSpecializedBackend(
@@ -63,11 +63,9 @@ export interface CreateSpecializedBackendOptions {
 }
 
 // @public
-export interface ExtensionPointFactoryMiddleware<T = unknown> {
+export interface ExtensionPointFactoryMiddleware<_T = unknown> {
   // (undocumented)
-  extensionPoint: ExtensionPoint<T>;
-  // (undocumented)
-  middleware: (original: T) => T;
+  $$type: '@backstage/ExtensionPointFactoryMiddleware';
 }
 
 // @public
diff --git a/packages/backend-app-api/src/wiring/BackendInitializer.test.ts b/packages/backend-app-api/src/wiring/BackendInitializer.test.ts
index c1801f0398..fb4da6ca05 100644
--- a/packages/backend-app-api/src/wiring/BackendInitializer.test.ts
+++ b/packages/backend-app-api/src/wiring/BackendInitializer.test.ts
@@ -2122,10 +2122,13 @@ describe('BackendInitializer', () => {
       });
 
       const init = new BackendInitializer(baseFactories, [
-        createExtensionPointFactoryMiddleware(extensionPoint, original => ({
-          ...original,
-          values: [...original.values, 'from-middleware'],
-        })),
+        createExtensionPointFactoryMiddleware({
+          extensionPoint,
+          middleware: async original => ({
+            ...original,
+            values: [...original.values, 'from-middleware'],
+          }),
+        }),
       ]);
 
       init.add(testPlugin);
@@ -2170,10 +2173,13 @@ describe('BackendInitializer', () => {
       });
 
       const init = new BackendInitializer(baseFactories, [
-        createExtensionPointFactoryMiddleware(extensionPointA, original => ({
-          ...original,
-          values: [...original.values, 'wrapped'],
-        })),
+        createExtensionPointFactoryMiddleware({
+          extensionPoint: extensionPointA,
+          middleware: async original => ({
+            ...original,
+            values: [...original.values, 'wrapped'],
+          }),
+        }),
       ]);
 
       init.add(testPlugin);
@@ -2215,14 +2221,20 @@ describe('BackendInitializer', () => {
       });
 
       const init = new BackendInitializer(baseFactories, [
-        createExtensionPointFactoryMiddleware(extensionPoint, original => ({
-          ...original,
-          values: [...original.values, 'first'],
-        })),
-        createExtensionPointFactoryMiddleware(extensionPoint, original => ({
-          ...original,
-          values: [...original.values, 'second'],
-        })),
+        createExtensionPointFactoryMiddleware({
+          extensionPoint,
+          middleware: async original => ({
+            ...original,
+            values: [...original.values, 'first'],
+          }),
+        }),
+        createExtensionPointFactoryMiddleware({
+          extensionPoint,
+          middleware: async original => ({
+            ...original,
+            values: [...original.values, 'second'],
+          }),
+        }),
       ]);
 
       init.add(testPlugin);
@@ -2262,13 +2274,13 @@ describe('BackendInitializer', () => {
       });
 
       const init = new BackendInitializer(baseFactories, [
-        createExtensionPointFactoryMiddleware(
-          unregisteredExtensionPoint,
-          original => ({
+        createExtensionPointFactoryMiddleware({
+          extensionPoint: unregisteredExtensionPoint,
+          middleware: async original => ({
             ...original,
             values: [...original.values, 'never-applied'],
           }),
-        ),
+        }),
       ]);
 
       init.add(testPlugin);
diff --git a/packages/backend-app-api/src/wiring/BackendInitializer.ts b/packages/backend-app-api/src/wiring/BackendInitializer.ts
index 211fb7dccc..9ff04652e6 100644
--- a/packages/backend-app-api/src/wiring/BackendInitializer.ts
+++ b/packages/backend-app-api/src/wiring/BackendInitializer.ts
@@ -29,6 +29,7 @@ import {
   ExtensionPointFactoryMiddleware,
   ServiceOrExtensionPoint,
 } from './types';
+import { OpaqueExtensionPointFactoryMiddleware } from '@internal/backend';
 // Direct internal import to avoid duplication
 // eslint-disable-next-line @backstage/no-relative-monorepo-imports
 import type {
@@ -210,8 +211,9 @@ export class BackendInitializer {
           },
         });
         for (const mw of this.#extensionPointFactoryMiddleware) {
-          if (mw.extensionPoint.id === ref.id) {
-            epImpl = (mw.middleware as (original: unknown) => unknown)(epImpl);
+          const internal = OpaqueExtensionPointFactoryMiddleware.toInternal(mw);
+          if (internal.extensionPointId === ref.id) {
+            epImpl = await internal.middleware(epImpl);
           }
         }
         result.set(name, epImpl);
diff --git a/packages/backend-app-api/src/wiring/types.ts b/packages/backend-app-api/src/wiring/types.ts
index 766d737dea..53cd8cfb5f 100644
--- a/packages/backend-app-api/src/wiring/types.ts
+++ b/packages/backend-app-api/src/wiring/types.ts
@@ -20,6 +20,7 @@ import {
   ServiceRef,
   ServiceFactory,
 } from '@backstage/backend-plugin-api';
+import { OpaqueExtensionPointFactoryMiddleware } from '@internal/backend';
 
 /**
  * A middleware entry that reimplements a specific extension point's output.
@@ -28,9 +29,8 @@ import {
  *
  * @public
  */
-export interface ExtensionPointFactoryMiddleware<T = unknown> {
-  extensionPoint: ExtensionPoint<T>;
-  middleware: (original: T) => T;
+export interface ExtensionPointFactoryMiddleware<_T = unknown> {
+  $$type: '@backstage/ExtensionPointFactoryMiddleware';
 }
 
 /**
@@ -39,14 +39,14 @@ export interface ExtensionPointFactoryMiddleware<T = unknown> {
  *
  * @public
  */
-export function createExtensionPointFactoryMiddleware<T>(
-  extensionPoint: ExtensionPoint<T>,
-  middleware: (original: T) => T,
-): ExtensionPointFactoryMiddleware {
-  return {
-    extensionPoint: extensionPoint as ExtensionPoint<unknown>,
-    middleware: middleware as (original: unknown) => unknown,
-  };
+export function createExtensionPointFactoryMiddleware<T>(options: {
+  extensionPoint: ExtensionPoint<T>;
+  middleware: (original: T) => Promise<T>;
+}): ExtensionPointFactoryMiddleware<T> {
+  return OpaqueExtensionPointFactoryMiddleware.createInstance('v1', {
+    extensionPointId: options.extensionPoint.id,
+    middleware: options.middleware as (original: unknown) => Promise<unknown>,
+  });
 }
 
 /**
diff --git a/packages/backend-defaults/report.api.md b/packages/backend-defaults/report.api.md
index ffc67e5473..a6702e59f9 100644
--- a/packages/backend-defaults/report.api.md
+++ b/packages/backend-defaults/report.api.md
@@ -5,18 +5,14 @@
 ```ts
 import { Backend } from '@backstage/backend-app-api';
 import { BackendFeature } from '@backstage/backend-plugin-api';
-import { createExtensionPointFactoryMiddleware } from '@backstage/backend-app-api';
-import { ExtensionPointFactoryMiddleware } from '@backstage/backend-app-api';
+import { ServiceFactory } from '@backstage/backend-plugin-api';
 
 // @public (undocumented)
-export function createBackend(options?: {
-  extensionPointFactoryMiddleware?: ExtensionPointFactoryMiddleware[];
-}): Backend;
+export function createBackend(): Backend;
 
-export { createExtensionPointFactoryMiddleware };
+// @public (undocumented)
+export const defaultServiceFactories: ServiceFactory[];
 
 // @public
 export const discoveryFeatureLoader: BackendFeature;
-
-export { ExtensionPointFactoryMiddleware };
 ```
diff --git a/packages/backend-defaults/src/CreateBackend.ts b/packages/backend-defaults/src/CreateBackend.ts
index e6976f6500..d069c17b99 100644
--- a/packages/backend-defaults/src/CreateBackend.ts
+++ b/packages/backend-defaults/src/CreateBackend.ts
@@ -14,11 +14,8 @@
  * limitations under the License.
  */
 
-import {
-  Backend,
-  createSpecializedBackend,
-  ExtensionPointFactoryMiddleware,
-} from '@backstage/backend-app-api';
+import { Backend, createSpecializedBackend } from '@backstage/backend-app-api';
+import { ServiceFactory } from '@backstage/backend-plugin-api';
 import { auditorServiceFactory } from '@backstage/backend-defaults/auditor';
 import { authServiceFactory } from '@backstage/backend-defaults/auth';
 import { cacheServiceFactory } from '@backstage/backend-defaults/cache';
@@ -46,7 +43,8 @@ import {
 } from '@backstage/backend-defaults/alpha';
 import { instanceMetadataServiceFactory } from './alpha/entrypoints/instanceMetadata/instanceMetadataServiceFactory';
 
-export const defaultServiceFactories = [
+/** @public */
+export const defaultServiceFactories: ServiceFactory[] = [
   auditorServiceFactory,
   authServiceFactory,
   cacheServiceFactory,
@@ -80,11 +78,6 @@ export const defaultServiceFactories = [
 /**
  * @public
  */
-export function createBackend(options?: {
-  extensionPointFactoryMiddleware?: ExtensionPointFactoryMiddleware[];
-}): Backend {
-  return createSpecializedBackend({
-    defaultServiceFactories,
-    extensionPointFactoryMiddleware: options?.extensionPointFactoryMiddleware,
-  });
+export function createBackend(): Backend {
+  return createSpecializedBackend({ defaultServiceFactories });
 }
diff --git a/packages/backend-defaults/src/index.ts b/packages/backend-defaults/src/index.ts
index eb3579c88a..ccf75ed9f8 100644
--- a/packages/backend-defaults/src/index.ts
+++ b/packages/backend-defaults/src/index.ts
@@ -20,7 +20,5 @@
  * @packageDocumentation
  */
 
-export { createBackend } from './CreateBackend';
-export type { ExtensionPointFactoryMiddleware } from '@backstage/backend-app-api';
-export { createExtensionPointFactoryMiddleware } from '@backstage/backend-app-api';
+export { createBackend, defaultServiceFactories } from './CreateBackend';
 export { discoveryFeatureLoader } from './discoveryFeatureLoader';
diff --git a/packages/backend-internal/.eslintrc.js b/packages/backend-internal/.eslintrc.js
new file mode 100644
index 0000000000..e487f765b2
--- /dev/null
+++ b/packages/backend-internal/.eslintrc.js
@@ -0,0 +1,5 @@
+module.exports = require('@backstage/cli/config/eslint-factory')(__dirname, {
+  rules: {
+    '@backstage/no-top-level-material-ui-4-imports': 'error',
+  },
+});
diff --git a/packages/backend-internal/README.md b/packages/backend-internal/README.md
new file mode 100644
index 0000000000..8994693a1b
--- /dev/null
+++ b/packages/backend-internal/README.md
@@ -0,0 +1,3 @@
+# @internal/backend
+
+This is an internal package used by the other backend packages. It does not get published to NPM, but instead inlined into consuming packages due to the `backstage.inline` flag in `package.json`.
diff --git a/packages/backend-internal/catalog-info.yaml b/packages/backend-internal/catalog-info.yaml
new file mode 100644
index 0000000000..37bc00382a
--- /dev/null
+++ b/packages/backend-internal/catalog-info.yaml
@@ -0,0 +1,9 @@
+apiVersion: backstage.io/v1alpha1
+kind: Component
+metadata:
+  name: internal-backend
+  title: '@internal/backend'
+spec:
+  lifecycle: experimental
+  type: backstage-node-library
+  owner: framework-maintainers
diff --git a/packages/backend-internal/package.json b/packages/backend-internal/package.json
new file mode 100644
index 0000000000..b043d1d42f
--- /dev/null
+++ b/packages/backend-internal/package.json
@@ -0,0 +1,28 @@
+{
+  "name": "@internal/backend",
+  "version": "0.0.1",
+  "backstage": {
+    "role": "node-library",
+    "inline": true
+  },
+  "private": true,
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "packages/backend-internal"
+  },
+  "license": "Apache-2.0",
+  "sideEffects": false,
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "lint": "backstage-cli package lint",
+    "test": "backstage-cli package test"
+  },
+  "devDependencies": {
+    "@backstage/cli": "workspace:^"
+  }
+}
diff --git a/packages/backend-internal/src/index.ts b/packages/backend-internal/src/index.ts
new file mode 100644
index 0000000000..add807a2c4
--- /dev/null
+++ b/packages/backend-internal/src/index.ts
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2026 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 { OpaqueExtensionPointFactoryMiddleware } from './wiring';
diff --git a/packages/backend-internal/src/wiring/OpaqueExtensionPointFactoryMiddleware.ts b/packages/backend-internal/src/wiring/OpaqueExtensionPointFactoryMiddleware.ts
new file mode 100644
index 0000000000..d94226ed93
--- /dev/null
+++ b/packages/backend-internal/src/wiring/OpaqueExtensionPointFactoryMiddleware.ts
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2026 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.
+ */
+
+import { OpaqueType } from '@internal/opaque';
+
+export const OpaqueExtensionPointFactoryMiddleware = OpaqueType.create<{
+  public: { $$type: '@backstage/ExtensionPointFactoryMiddleware' };
+  versions: {
+    readonly version: 'v1';
+    readonly extensionPointId: string;
+    readonly middleware: (original: unknown) => Promise<unknown>;
+  };
+}>({
+  type: '@backstage/ExtensionPointFactoryMiddleware',
+  versions: ['v1'],
+});
diff --git a/packages/backend-internal/src/wiring/index.ts b/packages/backend-internal/src/wiring/index.ts
new file mode 100644
index 0000000000..72c745bc9b
--- /dev/null
+++ b/packages/backend-internal/src/wiring/index.ts
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2026 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 { OpaqueExtensionPointFactoryMiddleware } from './OpaqueExtensionPointFactoryMiddleware';
diff --git a/yarn.lock b/yarn.lock
index 13b51ed309..38fbd212ef 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -9977,6 +9977,14 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@internal/backend@workspace:packages/backend-internal":
+  version: 0.0.0-use.local
+  resolution: "@internal/backend@workspace:packages/backend-internal"
+  dependencies:
+    "@backstage/cli": "workspace:^"
+  languageName: unknown
+  linkType: soft
+
 "@internal/cli@workspace:packages/cli-internal":
   version: 0.0.0-use.local
   resolution: "@internal/cli@workspace:packages/cli-internal"