diff --git a/packages/core/src/__mocks__/sign-in-experience.ts b/packages/core/src/__mocks__/sign-in-experience.ts
index 3be641ec5..19578d72d 100644
--- a/packages/core/src/__mocks__/sign-in-experience.ts
+++ b/packages/core/src/__mocks__/sign-in-experience.ts
@@ -28,7 +28,6 @@ export const mockSignInExperience: SignInExperience = {
   languageInfo: {
     autoDetect: true,
     fallbackLanguage: 'en',
-    fixedLanguage: 'zh-CN',
   },
   signInMethods: {
     username: SignInMethodState.Primary,
@@ -60,7 +59,6 @@ export const mockTermsOfUse: TermsOfUse = {
 export const mockLanguageInfo: LanguageInfo = {
   autoDetect: true,
   fallbackLanguage: 'en',
-  fixedLanguage: 'zh-CN',
 };
 
 export const mockSignInMethods: SignInMethods = {
diff --git a/packages/core/src/lib/sign-in-experience.test.ts b/packages/core/src/lib/sign-in-experience.test.ts
index e0d054a07..4b2e398e6 100644
--- a/packages/core/src/lib/sign-in-experience.test.ts
+++ b/packages/core/src/lib/sign-in-experience.test.ts
@@ -78,7 +78,6 @@ describe('validate language info', () => {
     await validateLanguageInfo({
       autoDetect: true,
       fallbackLanguage: 'zh-CN',
-      fixedLanguage: 'en',
     });
     expect(findAllCustomLanguageTags).toBeCalledTimes(1);
   });
@@ -89,7 +88,6 @@ describe('validate language info', () => {
       validateLanguageInfo({
         autoDetect: true,
         fallbackLanguage: builtInSupportedLanguage,
-        fixedLanguage: 'en',
       })
     ).resolves.not.toThrow();
     expect(findAllCustomLanguageTags).toBeCalledTimes(1);
@@ -103,7 +101,6 @@ describe('validate language info', () => {
       validateLanguageInfo({
         autoDetect: true,
         fallbackLanguage: customOnlySupportedLanguage,
-        fixedLanguage: 'en',
       })
     ).resolves.not.toThrow();
     expect(findAllCustomLanguageTags).toBeCalledTimes(1);
@@ -117,7 +114,6 @@ describe('validate language info', () => {
       validateLanguageInfo({
         autoDetect: true,
         fallbackLanguage: unsupportedLanguage,
-        fixedLanguage: 'en',
       })
     ).rejects.toMatchError(
       new RequestError({
diff --git a/packages/core/src/routes/custom-phrase.test.ts b/packages/core/src/routes/custom-phrase.test.ts
index 14452538d..35ecad9ac 100644
--- a/packages/core/src/routes/custom-phrase.test.ts
+++ b/packages/core/src/routes/custom-phrase.test.ts
@@ -57,7 +57,6 @@ const findDefaultSignInExperience = jest.fn(
     languageInfo: {
       autoDetect: true,
       fallbackLanguage: mockFallbackLanguage,
-      fixedLanguage: mockFallbackLanguage,
     },
   })
 );
diff --git a/packages/core/src/routes/phrase.content-language.test.ts b/packages/core/src/routes/phrase.content-language.test.ts
index 47b2e0f37..ab0d61bee 100644
--- a/packages/core/src/routes/phrase.content-language.test.ts
+++ b/packages/core/src/routes/phrase.content-language.test.ts
@@ -27,7 +27,6 @@ const findDefaultSignInExperience = jest.fn(async () => ({
   languageInfo: {
     autoDetect: true,
     fallbackLanguage,
-    fixedLanguage: fallbackLanguage,
   },
 }));
 
@@ -60,7 +59,6 @@ describe('when auto-detect is not enabled', () => {
       languageInfo: {
         autoDetect: false,
         fallbackLanguage: unsupportedLanguageX,
-        fixedLanguage: unsupportedLanguageX,
       },
     });
     const response = await phraseRequest
@@ -76,7 +74,6 @@ describe('when auto-detect is not enabled', () => {
         languageInfo: {
           autoDetect: false,
           fallbackLanguage,
-          fixedLanguage: fallbackLanguage,
         },
       });
     });
@@ -102,7 +99,6 @@ describe('when auto-detect is enabled', () => {
       languageInfo: {
         autoDetect: true,
         fallbackLanguage: unsupportedLanguageX,
-        fixedLanguage: unsupportedLanguageX,
       },
     });
     const response = await phraseRequest
@@ -118,7 +114,6 @@ describe('when auto-detect is enabled', () => {
         languageInfo: {
           autoDetect: true,
           fallbackLanguage,
-          fixedLanguage: fallbackLanguage,
         },
       });
     });
diff --git a/packages/core/src/routes/phrase.test.ts b/packages/core/src/routes/phrase.test.ts
index f51f0b633..0e39b4e8c 100644
--- a/packages/core/src/routes/phrase.test.ts
+++ b/packages/core/src/routes/phrase.test.ts
@@ -29,7 +29,6 @@ const findDefaultSignInExperience = jest.fn(
     languageInfo: {
       autoDetect: true,
       fallbackLanguage: customizedLanguage,
-      fixedLanguage: customizedLanguage,
     },
   })
 );
@@ -147,7 +146,6 @@ describe('when the application is not admin-console', () => {
       languageInfo: {
         autoDetect: false,
         fallbackLanguage: customizedLanguage,
-        fixedLanguage: customizedLanguage,
       },
     });
     await expect(phraseRequest.get('/phrase')).resolves.toHaveProperty('status', 200);
diff --git a/packages/schemas/src/foundations/jsonb-types.ts b/packages/schemas/src/foundations/jsonb-types.ts
index 2ff053e7f..fd4c9f6be 100644
--- a/packages/schemas/src/foundations/jsonb-types.ts
+++ b/packages/schemas/src/foundations/jsonb-types.ts
@@ -1,4 +1,4 @@
-import { hexColorRegEx, languageKeys } from '@logto/core-kit';
+import { hexColorRegEx } from '@logto/core-kit';
 import { languageTagGuard } from '@logto/language-kit';
 import { z } from 'zod';
 
@@ -124,8 +124,6 @@ export type TermsOfUse = z.infer<typeof termsOfUseGuard>;
 export const languageInfoGuard = z.object({
   autoDetect: z.boolean(),
   fallbackLanguage: languageTagGuard,
-  /** @deprecated */
-  fixedLanguage: z.enum(languageKeys),
 });
 
 export type LanguageInfo = z.infer<typeof languageInfoGuard>;
diff --git a/packages/schemas/src/seeds/sign-in-experience.ts b/packages/schemas/src/seeds/sign-in-experience.ts
index 487612704..0f3fcc8a3 100644
--- a/packages/schemas/src/seeds/sign-in-experience.ts
+++ b/packages/schemas/src/seeds/sign-in-experience.ts
@@ -20,7 +20,6 @@ export const defaultSignInExperience: Readonly<CreateSignInExperience> = {
   languageInfo: {
     autoDetect: true,
     fallbackLanguage: 'en',
-    fixedLanguage: 'en',
   },
   termsOfUse: {
     enabled: false,
diff --git a/packages/ui/src/__mocks__/logto.tsx b/packages/ui/src/__mocks__/logto.tsx
index 38a4324ba..f057568fd 100644
--- a/packages/ui/src/__mocks__/logto.tsx
+++ b/packages/ui/src/__mocks__/logto.tsx
@@ -178,7 +178,6 @@ export const mockSignInExperience: SignInExperience = {
   languageInfo: {
     autoDetect: true,
     fallbackLanguage: 'en',
-    fixedLanguage: 'zh-CN',
   },
   signInMethods: {
     username: SignInMethodState.Primary,