diff --git a/src/lib/features/change-request-segment-usage-service/change-request-segment-usage-read-model.test.ts b/src/lib/features/change-request-segment-usage-service/change-request-segment-usage-read-model.test.ts
index ed6567ef97..22c78f9a09 100644
--- a/src/lib/features/change-request-segment-usage-service/change-request-segment-usage-read-model.test.ts
+++ b/src/lib/features/change-request-segment-usage-service/change-request-segment-usage-read-model.test.ts
@@ -9,6 +9,7 @@ import { randomId } from '../../util/index.js';
 
 let db: ITestDb;
 let user: IUser;
+let user2: IUser;
 
 const CR_ID = 123456;
 const CR_ID_2 = 234567;
@@ -26,6 +27,10 @@ beforeAll(async () => {
         username: 'cr-creator',
     });
 
+    user2 = await db.stores.userStore.insert({
+        username: 'cr-creator-2',
+    });
+
     readModel = createChangeRequestSegmentUsageReadModel(db.rawDatabase);
 
     await db.stores.featureToggleStore.create('default', {
@@ -56,13 +61,14 @@ const createCR = async (
     state,
     changeRequestId = CR_ID,
     changeRequestTitle: string | null = CR_TITLE,
+    userId = user.id,
 ) => {
     await db.rawDatabase.table('change_requests').insert({
         id: changeRequestId,
         environment: 'default',
         state,
         project: 'default',
-        created_by: user.id,
+        created_by: userId,
         created_at: '2023-01-01 00:00:00',
         min_approvals: 1,
         title: changeRequestTitle,
@@ -212,7 +218,7 @@ test.each([
 
 test(`If the same strategy appears in multiple CRs with the same segment, each segment should be listed as its own entry`, async () => {
     await createCR('In review', CR_ID, CR_TITLE);
-    await createCR('In review', CR_ID_2, null);
+    await createCR('In review', CR_ID_2, null, user2.id);
 
     const segmentId = 3;
     const strategyId = randomId();
diff --git a/src/lib/features/feature-search/feature.search.e2e.test.ts b/src/lib/features/feature-search/feature.search.e2e.test.ts
index af8e74c109..6d5610e898 100644
--- a/src/lib/features/feature-search/feature.search.e2e.test.ts
+++ b/src/lib/features/feature-search/feature.search.e2e.test.ts
@@ -12,6 +12,7 @@ import {
     CREATE_FEATURE_STRATEGY,
     DEFAULT_PROJECT,
     type IUnleashStores,
+    TEST_AUDIT_USER,
     UPDATE_FEATURE_ENVIRONMENT,
 } from '../../types/index.js';
 import { DEFAULT_ENV } from '../../util/index.js';
@@ -76,6 +77,22 @@ beforeAll(async () => {
         ],
         'production',
     );
+
+    await app.services.userService.createUser(
+        {
+            username: 'admin@test.com',
+            rootRole: 1,
+        },
+        TEST_AUDIT_USER,
+    );
+
+    await app.services.userService.createUser(
+        {
+            username: 'admin2@test.com',
+            rootRole: 1,
+        },
+        TEST_AUDIT_USER,
+    );
 });
 
 afterAll(async () => {
@@ -1339,15 +1356,26 @@ const createChangeRequest = async ({
     feature,
     environment,
     state,
-}: { id: number; feature: string; environment: string; state: string }) => {
-    await db
-        .rawDatabase('change_requests')
-        .insert({ id, environment, state, project: 'default', created_by: 1 });
+    createdBy,
+}: {
+    id: number;
+    feature: string;
+    environment: string;
+    state: string;
+    createdBy: number;
+}) => {
+    await db.rawDatabase('change_requests').insert({
+        id,
+        environment,
+        state,
+        project: 'default',
+        created_by: createdBy,
+    });
     await db.rawDatabase('change_request_events').insert({
         id,
         feature,
         action: 'updateEnabled',
-        created_by: 1,
+        created_by: createdBy,
         change_request_id: id,
     });
 };
@@ -1361,48 +1389,56 @@ test('should return change request ids per environment', async () => {
         feature: 'my_feature_a',
         environment: 'production',
         state: 'In review',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 2,
         feature: 'my_feature_a',
         environment: 'production',
         state: 'Applied',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 3,
         feature: 'my_feature_a',
         environment: 'production',
         state: 'Cancelled',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 4,
         feature: 'my_feature_a',
         environment: 'production',
         state: 'Rejected',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 5,
         feature: 'my_feature_a',
         environment: 'development',
         state: 'Draft',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 6,
         feature: 'my_feature_a',
         environment: 'development',
         state: 'Scheduled',
+        createdBy: 1,
     });
     await createChangeRequest({
         id: 7,
         feature: 'my_feature_a',
         environment: 'development',
         state: 'Approved',
+        createdBy: 2,
     });
     await createChangeRequest({
         id: 8,
         feature: 'my_feature_b',
         environment: 'development',
         state: 'Approved',
+        createdBy: 3,
     });
 
     const { body } = await searchFeatures({});
diff --git a/src/migrations/20250529153326-cr-uniqueness.js b/src/migrations/20250529153326-cr-uniqueness.js
new file mode 100644
index 0000000000..1ec639abf6
--- /dev/null
+++ b/src/migrations/20250529153326-cr-uniqueness.js
@@ -0,0 +1,32 @@
+exports.up = (db, callback) => {
+    db.runSql(
+        `
+            WITH ranked AS (
+                SELECT id,
+                       ROW_NUMBER() OVER (
+                       PARTITION BY created_by, project, environment
+                       ORDER BY created_at DESC
+                   ) AS rn
+                FROM change_requests
+                WHERE state NOT IN ('Applied', 'Cancelled', 'Rejected', 'Scheduled')
+            )
+            UPDATE change_requests
+            SET state = 'Cancelled'
+            WHERE id IN (
+                SELECT id FROM ranked WHERE rn > 1
+            );
+
+            CREATE UNIQUE INDEX IF NOT EXISTS unique_pending_request_per_user_project_env
+                ON change_requests (created_by, project, environment)
+                WHERE state NOT IN ('Applied', 'Cancelled', 'Rejected', 'Scheduled');
+        `,
+        callback,
+    );
+};
+
+exports.down = (db, callback) => {
+    db.runSql(
+        ` DROP INDEX IF EXISTS unique_pending_request_per_user_project_env;`,
+        callback,
+    );
+};