diff --git a/pkg/apis/batch/validation/validation.go b/pkg/apis/batch/validation/validation.go
index cc8b72584fe..99cf5c3c954 100644
--- a/pkg/apis/batch/validation/validation.go
+++ b/pkg/apis/batch/validation/validation.go
@@ -914,6 +914,15 @@ func IsConditionTrue(list []batch.JobCondition, cType batch.JobConditionType) bo
 	return false
 }
 
+func IsConditionFalse(list []batch.JobCondition, cType batch.JobConditionType) bool {
+	for _, c := range list {
+		if c.Type == cType && c.Status == api.ConditionFalse {
+			return true
+		}
+	}
+	return false
+}
+
 func validateFailedIndexesNotOverlapCompleted(completedIndexesStr string, failedIndexesStr string, completions int32) error {
 	if len(completedIndexesStr) == 0 || len(failedIndexesStr) == 0 {
 		return nil
diff --git a/pkg/registry/batch/job/strategy.go b/pkg/registry/batch/job/strategy.go
index 8bde82debf7..23f343e754d 100644
--- a/pkg/registry/batch/job/strategy.go
+++ b/pkg/registry/batch/job/strategy.go
@@ -380,6 +380,11 @@ func getStatusValidationOptions(newJob, oldJob *batch.Job) batchvalidation.JobSt
 		isReadyChanged := !ptr.Equal(oldJob.Status.Ready, newJob.Status.Ready)
 		isTerminatingChanged := !ptr.Equal(oldJob.Status.Terminating, newJob.Status.Terminating)
 		isSuspendedWithZeroCompletions := ptr.Equal(newJob.Spec.Suspend, ptr.To(true)) && ptr.Equal(newJob.Spec.Completions, ptr.To[int32](0))
+		// Detect job resume via condition changes (JobSuspended: True -> False)
+		// This handles the case where the controller updates status after the user has already
+		// changed spec.suspend=false, which is the scenario from https://github.com/kubernetes/kubernetes/issues/134521
+		isJobResuming := batchvalidation.IsConditionTrue(oldJob.Status.Conditions, batch.JobSuspended) &&
+			batchvalidation.IsConditionFalse(newJob.Status.Conditions, batch.JobSuspended)
 
 		return batchvalidation.JobStatusValidationOptions{
 			// We allow to decrease the counter for succeeded pods for jobs which
@@ -397,7 +402,7 @@ func getStatusValidationOptions(newJob, oldJob *batch.Job) batchvalidation.JobSt
 			RejectFinishedJobWithActivePods:              isJobFinishedChanged || isActiveChanged,
 			RejectFinishedJobWithoutStartTime:            (isJobFinishedChanged || isStartTimeChanged) && !isSuspendedWithZeroCompletions,
 			RejectFinishedJobWithUncountedTerminatedPods: isJobFinishedChanged || isUncountedTerminatedPodsChanged,
-			RejectStartTimeUpdateForUnsuspendedJob:       isStartTimeChanged,
+			RejectStartTimeUpdateForUnsuspendedJob:       isStartTimeChanged && !isJobResuming,
 			RejectCompletionTimeBeforeStartTime:          isStartTimeChanged || isCompletionTimeChanged,
 			RejectMutatingCompletionTime:                 true,
 			RejectNotCompleteJobWithCompletionTime:       isJobCompleteChanged || isCompletionTimeChanged,
diff --git a/pkg/registry/batch/job/strategy_test.go b/pkg/registry/batch/job/strategy_test.go
index f11d5959924..e445251ebcf 100644
--- a/pkg/registry/batch/job/strategy_test.go
+++ b/pkg/registry/batch/job/strategy_test.go
@@ -2563,6 +2563,33 @@ func TestStatusStrategy_ValidateUpdate(t *testing.T) {
 				{Type: field.ErrorTypeRequired, Field: "status.startTime"},
 			},
 		},
+		"verify startTime can be updated when resuming job (JobSuspended: True -> False)": {
+			enableJobManagedBy: true,
+			job: &batch.Job{
+				ObjectMeta: validObjectMeta,
+				Status: batch.JobStatus{
+					StartTime: &now,
+					Conditions: []batch.JobCondition{
+						{
+							Type:   batch.JobSuspended,
+							Status: api.ConditionTrue,
+						},
+					},
+				},
+			},
+			newJob: &batch.Job{
+				ObjectMeta: validObjectMeta,
+				Status: batch.JobStatus{
+					StartTime: &nowPlusMinute,
+					Conditions: []batch.JobCondition{
+						{
+							Type:   batch.JobSuspended,
+							Status: api.ConditionFalse,
+						},
+					},
+				},
+			},
+		},
 		"invalid attempt to set completionTime before startTime": {
 			enableJobManagedBy: true,
 			job: &batch.Job{
diff --git a/test/integration/job/job_test.go b/test/integration/job/job_test.go
index d855c925e1c..24bbd002ab3 100644
--- a/test/integration/job/job_test.go
+++ b/test/integration/job/job_test.go
@@ -4095,6 +4095,85 @@ func TestSuspendJob(t *testing.T) {
 	}
 }
 
+// TestStartTimeUpdateOnResume verifies that the job controller can update startTime
+// when resuming a suspended job (https://github.com/kubernetes/kubernetes/issues/134521).
+func TestStartTimeUpdateOnResume(t *testing.T) {
+	featuregatetesting.SetFeatureGateDuringTest(t, feature.DefaultFeatureGate, features.JobManagedBy, true)
+
+	closeFn, restConfig, clientSet, ns := setup(t, "suspend-starttime-validation")
+	t.Cleanup(closeFn)
+	ctx, cancel := startJobControllerAndWaitForCaches(t, restConfig)
+	t.Cleanup(cancel)
+
+	job, err := createJobWithDefaults(ctx, clientSet, ns.Name, &batchv1.Job{
+		Spec: batchv1.JobSpec{
+			Parallelism: ptr.To[int32](1),
+			Completions: ptr.To[int32](2),
+			Suspend:     ptr.To(false),
+		},
+	})
+	if err != nil {
+		t.Fatalf("Failed to create Job: %v", err)
+	}
+
+	validateJobsPodsStatusOnly(ctx, t, clientSet, job, podsByStatus{
+		Active:      1,
+		Ready:       ptr.To[int32](0),
+		Terminating: ptr.To[int32](0),
+	})
+
+	job, err = clientSet.BatchV1().Jobs(ns.Name).Get(ctx, job.Name, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("Failed to get Job: %v", err)
+	}
+	if job.Status.StartTime == nil {
+		t.Fatalf("Job startTime was not set")
+	}
+
+	job.Spec.Suspend = ptr.To(true)
+	job, err = clientSet.BatchV1().Jobs(ns.Name).Update(ctx, job, metav1.UpdateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to suspend Job: %v", err)
+	}
+
+	validateJobsPodsStatusOnly(ctx, t, clientSet, job, podsByStatus{
+		Active:      0,
+		Ready:       ptr.To[int32](0),
+		Terminating: ptr.To[int32](0),
+	})
+
+	job, err = clientSet.BatchV1().Jobs(ns.Name).Get(ctx, job.Name, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("Failed to get Job: %v", err)
+	}
+	if getJobConditionStatus(ctx, job, batchv1.JobSuspended) != v1.ConditionTrue {
+		t.Fatalf("JobSuspended condition was not set to True")
+	}
+
+	job.Spec.Suspend = ptr.To(false)
+	job, err = clientSet.BatchV1().Jobs(ns.Name).Update(ctx, job, metav1.UpdateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to resume Job: %v", err)
+	}
+
+	validateJobsPodsStatusOnly(ctx, t, clientSet, job, podsByStatus{
+		Active:      1,
+		Ready:       ptr.To[int32](0),
+		Terminating: ptr.To[int32](0),
+	})
+
+	job, err = clientSet.BatchV1().Jobs(ns.Name).Get(ctx, job.Name, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("Failed to get Job: %v", err)
+	}
+	if getJobConditionStatus(ctx, job, batchv1.JobSuspended) != v1.ConditionFalse {
+		t.Error("JobSuspended condition was not set to False")
+	}
+	if job.Status.StartTime == nil {
+		t.Error("Job startTime was not set after resume")
+	}
+}
+
 // TestSuspendJobWithZeroCompletions verifies the suspended Job with
 // completions=0 is marked as Complete.
 func TestSuspendJobWithZeroCompletions(t *testing.T) {