diff --git a/packages/core/src/routes/organization-scopes.test.ts b/packages/core/src/routes/organization-scopes.test.ts
new file mode 100644
index 000000000..a8216ac4b
--- /dev/null
+++ b/packages/core/src/routes/organization-scopes.test.ts
@@ -0,0 +1,23 @@
+import { UniqueIntegrityConstraintViolationError } from 'slonik';
+
+import RequestError from '#src/errors/RequestError/index.js';
+import { MockTenant } from '#src/test-utils/tenant.js';
+
+import { OrganizationScopeActions } from './organization-scopes.js';
+
+describe('OrganizationScopeActions', () => {
+  it('should throw RequestError if UniqueIntegrityConstraintViolationError is thrown inside', async () => {
+    const tenantContext = new MockTenant(undefined, {
+      organizationScopes: {
+        insert: async () => {
+          throw new UniqueIntegrityConstraintViolationError(new Error('test'), 'unique');
+        },
+      },
+    });
+    const actions = new OrganizationScopeActions(tenantContext.queries.organizationScopes);
+
+    await expect(actions.post({ name: 'test' })).rejects.toThrowError(
+      new RequestError({ code: 'entity.duplicate_value_of_unique_field', field: 'name' })
+    );
+  });
+});
diff --git a/packages/core/src/routes/organization-scopes.ts b/packages/core/src/routes/organization-scopes.ts
index a65045223..092fc8581 100644
--- a/packages/core/src/routes/organization-scopes.ts
+++ b/packages/core/src/routes/organization-scopes.ts
@@ -1,9 +1,36 @@
-import { OrganizationScopes } from '@logto/schemas';
+import {
+  type CreateOrganizationScope,
+  type OrganizationScope,
+  type OrganizationScopeKeys,
+  OrganizationScopes,
+} from '@logto/schemas';
+import { UniqueIntegrityConstraintViolationError } from 'slonik';
 
+import RequestError from '#src/errors/RequestError/index.js';
 import SchemaRouter, { SchemaActions } from '#src/utils/SchemaRouter.js';
 
 import { type AuthedRouter, type RouterInitArgs } from './types.js';
 
+export class OrganizationScopeActions extends SchemaActions<
+  OrganizationScopeKeys,
+  CreateOrganizationScope,
+  OrganizationScope
+> {
+  override async post(
+    data: Omit<CreateOrganizationScope, 'id'>
+  ): Promise<Readonly<OrganizationScope>> {
+    try {
+      return await super.post(data);
+    } catch (error: unknown) {
+      if (error instanceof UniqueIntegrityConstraintViolationError) {
+        throw new RequestError({ code: 'entity.duplicate_value_of_unique_field', field: 'name' });
+      }
+
+      throw error;
+    }
+  }
+}
+
 export default function organizationScopeRoutes<T extends AuthedRouter>(
   ...[
     originalRouter,
@@ -12,7 +39,10 @@ export default function organizationScopeRoutes<T extends AuthedRouter>(
     },
   ]: RouterInitArgs<T>
 ) {
-  const router = new SchemaRouter(OrganizationScopes, new SchemaActions(organizationScopes));
+  const router = new SchemaRouter(
+    OrganizationScopes,
+    new OrganizationScopeActions(organizationScopes)
+  );
 
   originalRouter.use(router.routes());
 }
diff --git a/packages/integration-tests/src/tests/api/organization-scope.test.ts b/packages/integration-tests/src/tests/api/organization-scope.test.ts
index d6b8d3535..ac46ab0d2 100644
--- a/packages/integration-tests/src/tests/api/organization-scope.test.ts
+++ b/packages/integration-tests/src/tests/api/organization-scope.test.ts
@@ -1,4 +1,7 @@
+import assert from 'node:assert';
+
 import { generateStandardId } from '@logto/shared';
+import { isKeyInObject } from '@silverhand/essentials';
 import { HTTPError } from 'got';
 
 import {
@@ -12,6 +15,19 @@ import {
 const randomId = () => generateStandardId(4);
 
 describe('organization scopes', () => {
+  it('should fail if the name of the new organization scope already exists', async () => {
+    const name = 'test' + randomId();
+    await createOrganizationScope(name);
+    const response = await createOrganizationScope(name).catch((error: unknown) => error);
+
+    assert(response instanceof HTTPError);
+
+    const { statusCode, body: raw } = response.response;
+    const body: unknown = JSON.parse(String(raw));
+    expect(statusCode).toBe(400);
+    expect(isKeyInObject(body, 'code') && body.code).toBe('entity.duplicate_value_of_unique_field');
+  });
+
   it('should get organization scopes successfully', async () => {
     const [name1, name2] = ['test' + randomId(), 'test' + randomId()];
     await createOrganizationScope(name1, 'A test organization scope.');
diff --git a/packages/phrases/src/locales/de/errors/entity.ts b/packages/phrases/src/locales/de/errors/entity.ts
index b645df292..6c976a91c 100644
--- a/packages/phrases/src/locales/de/errors/entity.ts
+++ b/packages/phrases/src/locales/de/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} existiert nicht.',
   not_exists_with_id: '{{name}} mit ID `{{id}}` existiert nicht.',
   not_found: 'Die Ressource wurde nicht gefunden.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/en/errors/entity.ts b/packages/phrases/src/locales/en/errors/entity.ts
index 8c0c22136..25bd3b6cf 100644
--- a/packages/phrases/src/locales/en/errors/entity.ts
+++ b/packages/phrases/src/locales/en/errors/entity.ts
@@ -5,6 +5,7 @@ const entity = {
   not_exists: 'The {{name}} does not exist.',
   not_exists_with_id: 'The {{name}} with ID `{{id}}` does not exist.',
   not_found: 'The resource does not exist.',
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/es/errors/entity.ts b/packages/phrases/src/locales/es/errors/entity.ts
index 0e291941d..80432fccc 100644
--- a/packages/phrases/src/locales/es/errors/entity.ts
+++ b/packages/phrases/src/locales/es/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: 'El {{name}} no existe.',
   not_exists_with_id: 'El {{name}} con ID `{{id}}` no existe.',
   not_found: 'El recurso no existe.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/fr/errors/entity.ts b/packages/phrases/src/locales/fr/errors/entity.ts
index 6a83ca638..58f4bb2cf 100644
--- a/packages/phrases/src/locales/fr/errors/entity.ts
+++ b/packages/phrases/src/locales/fr/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: "Le {{name}} n'existe pas.",
   not_exists_with_id: "Le {{name}} avec l'ID `{{id}}` n'existe pas.",
   not_found: "La ressource n'existe pas.",
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/it/errors/entity.ts b/packages/phrases/src/locales/it/errors/entity.ts
index b26f18c75..c5a988479 100644
--- a/packages/phrases/src/locales/it/errors/entity.ts
+++ b/packages/phrases/src/locales/it/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} non esiste.',
   not_exists_with_id: '{{name}} con ID `{{id}}` non esiste.',
   not_found: 'La risorsa non esiste.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/ja/errors/entity.ts b/packages/phrases/src/locales/ja/errors/entity.ts
index 7ba5b4ab8..3a0094d11 100644
--- a/packages/phrases/src/locales/ja/errors/entity.ts
+++ b/packages/phrases/src/locales/ja/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}}は存在しません。',
   not_exists_with_id: 'IDが`{{id}}`の{{name}}は存在しません。',
   not_found: 'リソースが存在しません。',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/ko/errors/entity.ts b/packages/phrases/src/locales/ko/errors/entity.ts
index a81639331..5f3abba7d 100644
--- a/packages/phrases/src/locales/ko/errors/entity.ts
+++ b/packages/phrases/src/locales/ko/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}}는 존재하지 않아요.',
   not_exists_with_id: '{{id}} ID를 가진 {{name}}는 존재하지 않아요.',
   not_found: '리소스가 존재하지 않아요.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/pl-pl/errors/entity.ts b/packages/phrases/src/locales/pl-pl/errors/entity.ts
index 723a3e7e2..7cfbab2f9 100644
--- a/packages/phrases/src/locales/pl-pl/errors/entity.ts
+++ b/packages/phrases/src/locales/pl-pl/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} nie istnieje.',
   not_exists_with_id: '{{name}} o identyfikatorze `{{id}}` nie istnieje.',
   not_found: 'Zasób nie istnieje.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/pt-br/errors/entity.ts b/packages/phrases/src/locales/pt-br/errors/entity.ts
index d8a1c636f..1a7ad53cc 100644
--- a/packages/phrases/src/locales/pt-br/errors/entity.ts
+++ b/packages/phrases/src/locales/pt-br/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: 'O {{name}} não existe.',
   not_exists_with_id: 'O {{name}} com ID `{{id}}` não existe.',
   not_found: 'O recurso não existe.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/pt-pt/errors/entity.ts b/packages/phrases/src/locales/pt-pt/errors/entity.ts
index be19d9f16..9652b4abe 100644
--- a/packages/phrases/src/locales/pt-pt/errors/entity.ts
+++ b/packages/phrases/src/locales/pt-pt/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} não existe.',
   not_exists_with_id: '{{name}} com o ID `{{id}}` não existe.',
   not_found: 'O recurso não existe.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/ru/errors/entity.ts b/packages/phrases/src/locales/ru/errors/entity.ts
index 10ebe43cf..5b59de227 100644
--- a/packages/phrases/src/locales/ru/errors/entity.ts
+++ b/packages/phrases/src/locales/ru/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} не существует.',
   not_exists_with_id: '{{name}} с ID `{{id}}` не существует.',
   not_found: 'Ресурс не существует.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/tr-tr/errors/entity.ts b/packages/phrases/src/locales/tr-tr/errors/entity.ts
index e08462fd9..dc2d6e968 100644
--- a/packages/phrases/src/locales/tr-tr/errors/entity.ts
+++ b/packages/phrases/src/locales/tr-tr/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} mevcut değil.',
   not_exists_with_id: ' `{{id}}` id kimliğine sahip {{name}} mevcut değil.',
   not_found: 'Kaynak mevcut değil.',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/zh-cn/errors/entity.ts b/packages/phrases/src/locales/zh-cn/errors/entity.ts
index e2813140a..d4ed8a178 100644
--- a/packages/phrases/src/locales/zh-cn/errors/entity.ts
+++ b/packages/phrases/src/locales/zh-cn/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '该 {{name}} 不存在。',
   not_exists_with_id: 'ID 为 `{{id}}` 的 {{name}} 不存在。',
   not_found: '该资源不存在。',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/zh-hk/errors/entity.ts b/packages/phrases/src/locales/zh-hk/errors/entity.ts
index 92366f524..be338f09f 100644
--- a/packages/phrases/src/locales/zh-hk/errors/entity.ts
+++ b/packages/phrases/src/locales/zh-hk/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '該 {{name}} 不存在。',
   not_exists_with_id: 'ID 為 `{{id}}` 的 {{name}} 不存在。',
   not_found: '該資源不存在。',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);
diff --git a/packages/phrases/src/locales/zh-tw/errors/entity.ts b/packages/phrases/src/locales/zh-tw/errors/entity.ts
index 38c6549b4..0bed3b82b 100644
--- a/packages/phrases/src/locales/zh-tw/errors/entity.ts
+++ b/packages/phrases/src/locales/zh-tw/errors/entity.ts
@@ -5,6 +5,8 @@ const entity = {
   not_exists: '{{name}} 不存在。',
   not_exists_with_id: 'ID 為 `{{id}}` 的 {{name}} 不存在。',
   not_found: '資源不存在。',
+  /** UNTRANSLATED */
+  duplicate_value_of_unique_field: 'The value of the unique field `{{field}}` is duplicated.',
 };
 
 export default Object.freeze(entity);