diff --git a/.changeset/bright-bulldogs-whisper.md b/.changeset/bright-bulldogs-whisper.md
new file mode 100644
index 0000000000..bedc367856
--- /dev/null
+++ b/.changeset/bright-bulldogs-whisper.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-linguist-backend': patch
+---
+
+Migrated to support new auth services.
diff --git a/plugins/linguist-backend/api-report.md b/plugins/linguist-backend/api-report.md
index 95bdc858ee..31892fcdb1 100644
--- a/plugins/linguist-backend/api-report.md
+++ b/plugins/linguist-backend/api-report.md
@@ -3,6 +3,7 @@
 > Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
 
 ```ts
+import { AuthService } from '@backstage/backend-plugin-api';
 import { BackendFeature } from '@backstage/backend-plugin-api';
 import { CatalogProcessor } from '@backstage/plugin-catalog-node';
 import { CatalogProcessorCache } from '@backstage/plugin-catalog-node';
@@ -10,6 +11,7 @@ import { Config } from '@backstage/config';
 import { DiscoveryService } from '@backstage/backend-plugin-api';
 import { Entity } from '@backstage/catalog-model';
 import express from 'express';
+import { HttpAuthService } from '@backstage/backend-plugin-api';
 import { HumanDuration } from '@backstage/types';
 import { Languages } from '@backstage/plugin-linguist-common';
 import { LanguageType } from '@backstage/plugin-linguist-common';
@@ -94,6 +96,8 @@ export interface PluginOptions {
 
 // @public (undocumented)
 export interface RouterOptions {
+  // (undocumented)
+  auth?: AuthService;
   // (undocumented)
   config?: Config;
   // (undocumented)
@@ -101,6 +105,8 @@ export interface RouterOptions {
   // (undocumented)
   discovery: PluginEndpointDiscovery;
   // (undocumented)
+  httpAuth?: HttpAuthService;
+  // (undocumented)
   linguistBackendApi?: LinguistBackendApi;
   // (undocumented)
   logger: Logger;
diff --git a/plugins/linguist-backend/src/api/LinguistBackendClient.test.ts b/plugins/linguist-backend/src/api/LinguistBackendClient.test.ts
index 55c74df424..be25fa9821 100644
--- a/plugins/linguist-backend/src/api/LinguistBackendClient.test.ts
+++ b/plugins/linguist-backend/src/api/LinguistBackendClient.test.ts
@@ -17,7 +17,6 @@
 import {
   getVoidLogger,
   ReadTreeResponse,
-  ServerTokenManager,
   UrlReader,
 } from '@backstage/backend-common';
 import { CatalogApi, GetEntitiesResponse } from '@backstage/catalog-client';
@@ -27,6 +26,7 @@ import { LinguistBackendStore } from '../db';
 import { kindOrDefault, LinguistBackendClient } from './LinguistBackendClient';
 import fs from 'fs-extra';
 import { LINGUIST_ANNOTATION } from '@backstage/plugin-linguist-common';
+import { mockServices } from '@backstage/backend-test-utils';
 
 const linguistResultMock = Promise.resolve({
   files: {
@@ -97,13 +97,11 @@ describe('Linguist backend API', () => {
     getEntityByRef: jest.fn(),
   } as any;
 
-  const tokenManager = ServerTokenManager.noop();
-
   const api = new LinguistBackendClient(
     logger,
     store,
     urlReader,
-    tokenManager,
+    mockServices.auth(),
     catalogApi,
   );
 
@@ -230,7 +228,7 @@ describe('Linguist backend API', () => {
       logger,
       store,
       urlReader,
-      tokenManager,
+      mockServices.auth(),
       catalogApi,
       { days: 5 },
     );
@@ -353,7 +351,7 @@ describe('Linguist backend API', () => {
       logger,
       store,
       urlReader,
-      tokenManager,
+      mockServices.auth(),
       catalogApi,
       undefined,
       2,
diff --git a/plugins/linguist-backend/src/api/LinguistBackendClient.ts b/plugins/linguist-backend/src/api/LinguistBackendClient.ts
index 1be4a7d288..d2c2a9124a 100644
--- a/plugins/linguist-backend/src/api/LinguistBackendClient.ts
+++ b/plugins/linguist-backend/src/api/LinguistBackendClient.ts
@@ -25,7 +25,7 @@ import {
   GetEntitiesRequest,
   CatalogApi,
 } from '@backstage/catalog-client';
-import { TokenManager, UrlReader } from '@backstage/backend-common';
+import { UrlReader } from '@backstage/backend-common';
 
 import { DateTime } from 'luxon';
 import { LINGUIST_ANNOTATION } from '@backstage/plugin-linguist-common';
@@ -40,6 +40,7 @@ import {
 import { assertError } from '@backstage/errors';
 import { HumanDuration } from '@backstage/types';
 import { Results } from 'linguist-js/dist/types';
+import { type AuthService } from '@backstage/backend-plugin-api';
 
 /** @public */
 export interface LinguistBackendApi {
@@ -52,7 +53,7 @@ export class LinguistBackendClient implements LinguistBackendApi {
   private readonly logger: Logger;
   private readonly store: LinguistBackendStore;
   private readonly urlReader: UrlReader;
-  private readonly tokenManager: TokenManager;
+  private readonly auth: AuthService;
 
   private readonly catalogApi: CatalogApi;
   private readonly age?: HumanDuration;
@@ -64,7 +65,7 @@ export class LinguistBackendClient implements LinguistBackendApi {
     logger: Logger,
     store: LinguistBackendStore,
     urlReader: UrlReader,
-    tokenManager: TokenManager,
+    auth: AuthService,
     catalogApi: CatalogApi,
     age?: HumanDuration,
     batchSize?: number,
@@ -75,7 +76,7 @@ export class LinguistBackendClient implements LinguistBackendApi {
     this.logger = logger;
     this.store = store;
     this.urlReader = urlReader;
-    this.tokenManager = tokenManager;
+    this.auth = auth;
     this.catalogApi = catalogApi;
     this.batchSize = batchSize;
     this.age = age;
@@ -114,7 +115,10 @@ export class LinguistBackendClient implements LinguistBackendApi {
       fields: ['kind', 'metadata'],
     };
 
-    const { token } = await this.tokenManager.getToken();
+    const { token } = await this.auth.getPluginRequestToken({
+      onBehalfOf: await this.auth.getOwnServiceCredentials(),
+      targetPluginId: 'catalog',
+    });
     const response = await this.catalogApi.getEntities(request, { token });
     const entities = response.items;
 
@@ -130,7 +134,10 @@ export class LinguistBackendClient implements LinguistBackendApi {
     const allEntities = await this.store.getAllEntities();
 
     for (const entityRef of allEntities) {
-      const { token } = await this.tokenManager.getToken();
+      const { token } = await this.auth.getPluginRequestToken({
+        onBehalfOf: await this.auth.getOwnServiceCredentials(),
+        targetPluginId: 'catalog',
+      });
       const result = await this.catalogApi.getEntityByRef(entityRef, { token });
 
       if (!result) {
@@ -155,7 +162,10 @@ export class LinguistBackendClient implements LinguistBackendApi {
     );
 
     for (const entityRef of entities) {
-      const { token } = await this.tokenManager.getToken();
+      const { token } = await this.auth.getPluginRequestToken({
+        onBehalfOf: await this.auth.getOwnServiceCredentials(),
+        targetPluginId: 'catalog',
+      });
       const entity = await this.catalogApi.getEntityByRef(entityRef, {
         token,
       });
diff --git a/plugins/linguist-backend/src/plugin.ts b/plugins/linguist-backend/src/plugin.ts
index cbf18d9ebe..e569b00233 100644
--- a/plugins/linguist-backend/src/plugin.ts
+++ b/plugins/linguist-backend/src/plugin.ts
@@ -32,6 +32,8 @@ export const linguistPlugin = createBackendPlugin({
   register(env) {
     env.registerInit({
       deps: {
+        auth: coreServices.auth,
+        httpAuth: coreServices.httpAuth,
         logger: coreServices.logger,
         config: coreServices.rootConfig,
         reader: coreServices.urlReader,
@@ -42,6 +44,8 @@ export const linguistPlugin = createBackendPlugin({
         httpRouter: coreServices.httpRouter,
       },
       async init({
+        auth,
+        httpAuth,
         logger,
         config,
         reader,
@@ -53,6 +57,8 @@ export const linguistPlugin = createBackendPlugin({
       }) {
         httpRouter.use(
           await createRouterFromConfig({
+            auth,
+            httpAuth,
             logger: loggerToWinstonLogger(logger),
             config,
             reader,
diff --git a/plugins/linguist-backend/src/service/router.ts b/plugins/linguist-backend/src/service/router.ts
index d29943c38b..7d64edc82e 100644
--- a/plugins/linguist-backend/src/service/router.ts
+++ b/plugins/linguist-backend/src/service/router.ts
@@ -15,6 +15,7 @@
  */
 
 import {
+  createLegacyAuthAdapters,
   errorHandler,
   PluginDatabaseManager,
   PluginEndpointDiscovery,
@@ -35,6 +36,7 @@ import { HumanDuration } from '@backstage/types';
 import { CatalogClient } from '@backstage/catalog-client';
 import { LinguistBackendClient } from '../api/LinguistBackendClient';
 import { Config } from '@backstage/config';
+import { AuthService, HttpAuthService } from '@backstage/backend-plugin-api';
 
 /** @public */
 export interface PluginOptions {
@@ -56,6 +58,8 @@ export interface RouterOptions {
   discovery: PluginEndpointDiscovery;
   scheduler?: PluginTaskScheduler;
   config?: Config;
+  auth?: AuthService;
+  httpAuth?: HttpAuthService;
 }
 
 /** @public */
@@ -63,7 +67,7 @@ export async function createRouter(
   pluginOptions: PluginOptions,
   routerOptions: RouterOptions,
 ): Promise<express.Router> {
-  const { logger, reader, database, discovery, scheduler, tokenManager } =
+  const { logger, reader, database, discovery, scheduler, tokenManager, auth } =
     routerOptions;
 
   const {
@@ -81,13 +85,19 @@ export async function createRouter(
 
   const catalogClient = new CatalogClient({ discoveryApi: discovery });
 
+  const { auth: adaptedAuth } = createLegacyAuthAdapters({
+    auth,
+    tokenManager: tokenManager,
+    discovery: discovery,
+  });
+
   const linguistBackendClient =
     routerOptions.linguistBackendApi ||
     new LinguistBackendClient(
       logger,
       linguistBackendStore,
       reader,
-      tokenManager,
+      adaptedAuth,
       catalogClient,
       age,
       batchSize,