diff --git a/go-controller/pkg/clustermanager/userdefinednetwork/controller.go b/go-controller/pkg/clustermanager/userdefinednetwork/controller.go
index 10a1fee9dd..f007812b92 100644
--- a/go-controller/pkg/clustermanager/userdefinednetwork/controller.go
+++ b/go-controller/pkg/clustermanager/userdefinednetwork/controller.go
@@ -263,14 +263,14 @@ func (c *Controller) ReconcileNetAttachDef(key string) error {
 // ReconcileNamespace enqueue relevant Cluster UDN CR requests following namespace events.
 func (c *Controller) ReconcileNamespace(key string) error {
 	namespace, err := c.namespaceInformer.Lister().Get(key)
-	if err != nil {
-		// Ignore removed namespaces
-		if apierrors.IsNotFound(err) {
-			return nil
-		}
+	if err != nil && !apierrors.IsNotFound(err) {
 		return fmt.Errorf("failed to get namespace %q from cache: %w", key, err)
 	}
-	namespaceLabels := labels.Set(namespace.Labels)
+
+	var namespaceLabels labels.Set
+	if namespace != nil {
+		namespaceLabels = namespace.Labels
+	}
 
 	c.namespaceTrackerLock.RLock()
 	defer c.namespaceTrackerLock.RUnlock()
@@ -278,8 +278,16 @@ func (c *Controller) ReconcileNamespace(key string) error {
 	for cudnName, affectedNamespaces := range c.namespaceTracker {
 		affectedNamespace := affectedNamespaces.Has(key)
 
-		selectedNamespace := false
+		// For deleted namespaces, only reconcile if tracked
+		if namespace == nil {
+			if affectedNamespace {
+				klog.Errorf("BUG: namespace %q was deleted but still tracked by ClusterUDN %q, forcing reconcile to cleanup", key, cudnName)
+				c.cudnController.Reconcile(cudnName)
+			}
+			continue
+		}
 
+		selectedNamespace := false
 		if !affectedNamespace {
 			cudn, err := c.cudnLister.Get(cudnName)
 			if err != nil {
@@ -656,6 +664,10 @@ func (c *Controller) getSelectedNamespaces(sel metav1.LabelSelector) (sets.Set[s
 		return nil, fmt.Errorf("failed to list namespaces: %w", err)
 	}
 	for _, selectedNs := range selectedNamespacesList {
+		if !selectedNs.DeletionTimestamp.IsZero() {
+			klog.V(5).Infof("Namespace %s is being deleted, skipping", selectedNs.Name)
+			continue
+		}
 		selectedNamespaces.Insert(selectedNs.Name)
 	}
 	return selectedNamespaces, nil
diff --git a/go-controller/pkg/clustermanager/userdefinednetwork/controller_test.go b/go-controller/pkg/clustermanager/userdefinednetwork/controller_test.go
index 08791e9bf4..ddde9b7ed8 100644
--- a/go-controller/pkg/clustermanager/userdefinednetwork/controller_test.go
+++ b/go-controller/pkg/clustermanager/userdefinednetwork/controller_test.go
@@ -1202,6 +1202,32 @@ var _ = Describe("User Defined Network Controller", func() {
 			Expect(err).To(MatchError(expectedErr))
 		})
 
+		It("when namespace without pods is being deleted, should delete NAD in that namespace", func() {
+			const cudnName = "test-network"
+			testNs := testNamespace("blue")
+			cudn := testClusterUDN(cudnName, testNs.Name)
+			expectedNAD := testClusterUdnNAD(cudnName, testNs.Name)
+			c := newTestController(renderNadStub(expectedNAD), cudn, testNs)
+			Expect(c.Run()).To(Succeed())
+
+			By("verify NAD is created in namespace")
+			Eventually(func() error {
+				_, err := cs.NetworkAttchDefClient.K8sCniCncfIoV1().NetworkAttachmentDefinitions(testNs.Name).Get(context.Background(), cudnName, metav1.GetOptions{})
+				return err
+			}).Should(Succeed())
+
+			By("mark namespace as terminating")
+			testNs.DeletionTimestamp = &metav1.Time{Time: time.Now()}
+			_, err := cs.KubeClient.CoreV1().Namespaces().Update(context.Background(), testNs, metav1.UpdateOptions{})
+			Expect(err).ToNot(HaveOccurred())
+
+			By("verify NAD is deleted")
+			Eventually(func() bool {
+				_, err := cs.NetworkAttchDefClient.K8sCniCncfIoV1().NetworkAttachmentDefinitions(testNs.Name).Get(context.Background(), cudnName, metav1.GetOptions{})
+				return apierrors.IsNotFound(err)
+			}).Should(BeTrue(), "NAD should be deleted when namespace is terminating")
+		})
+
 		It("when CR is deleted, CR has no finalizer, should succeed", func() {
 			deletedCUDN := testClusterUDN("test", "blue")
 			deletedCUDN.Finalizers = []string{}
diff --git a/go-controller/pkg/clustermanager/userdefinednetwork/notifier/namespace.go b/go-controller/pkg/clustermanager/userdefinednetwork/notifier/namespace.go
index 90ff81befc..d6dbf634f2 100644
--- a/go-controller/pkg/clustermanager/userdefinednetwork/notifier/namespace.go
+++ b/go-controller/pkg/clustermanager/userdefinednetwork/notifier/namespace.go
@@ -46,10 +46,11 @@ func NewNamespaceNotifier(nsInformer corev1informer.NamespaceInformer, subscribe
 func (c *NamespaceNotifier) needUpdate(old, new *corev1.Namespace) bool {
 	nsCreated := old == nil && new != nil
 	nsDeleted := old != nil && new == nil
+	nsDeleting := new != nil && !new.DeletionTimestamp.IsZero()
 	nsLabelsChanged := old != nil && new != nil &&
 		!reflect.DeepEqual(old.Labels, new.Labels)
 
-	return nsCreated || nsDeleted || nsLabelsChanged
+	return nsCreated || nsDeleted || nsDeleting || nsLabelsChanged
 }
 
 // reconcile notify subscribers with the request namespace key following namespace events.
diff --git a/test/e2e/network_segmentation.go b/test/e2e/network_segmentation.go
index d1591e4781..9f9e91f584 100644
--- a/test/e2e/network_segmentation.go
+++ b/test/e2e/network_segmentation.go
@@ -1315,6 +1315,40 @@ spec:
 			}
 		})
 
+		It("should delete NAD when target namespace is terminating", func() {
+			testTerminatingNs := f.Namespace.Name + "terminating"
+
+			By("add new target namespace to CR namespace-selector")
+			patch := fmt.Sprintf(`[{"op": "add", "path": "./spec/namespaceSelector/matchExpressions/0/values/-", "value": "%s"}]`, testTerminatingNs)
+			_, err := e2ekubectl.RunKubectl("", "patch", clusterUserDefinedNetworkResource, testClusterUdnName, "--type=json", "-p="+patch)
+			Expect(err).NotTo(HaveOccurred())
+
+			By("create the target namespace")
+			_, err = cs.CoreV1().Namespaces().Create(context.Background(), &v1.Namespace{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:   testTerminatingNs,
+					Labels: map[string]string{RequiredUDNNamespaceLabel: ""},
+				}}, metav1.CreateOptions{})
+			Expect(err).NotTo(HaveOccurred())
+
+			By("verify NAD is created in the namespace")
+			Eventually(func() error {
+				_, err := nadClient.NetworkAttachmentDefinitions(testTerminatingNs).Get(context.Background(), testClusterUdnName, metav1.GetOptions{})
+				return err
+			}, time.Second*15, time.Second*1).Should(Succeed(), "NAD should be created in target namespace")
+
+			By("delete the namespace to trigger termination")
+			err = cs.CoreV1().Namespaces().Delete(context.Background(), testTerminatingNs, metav1.DeleteOptions{})
+			Expect(err).NotTo(HaveOccurred())
+
+			By("verify NAD is deleted from the terminating namespace")
+			Eventually(func() bool {
+				_, err := nadClient.NetworkAttachmentDefinitions(testTerminatingNs).Get(context.Background(), testClusterUdnName, metav1.GetOptions{})
+				return err != nil && kerrors.IsNotFound(err)
+			}, time.Second*30, time.Second*1).Should(BeTrue(),
+				"NAD should be deleted when namespace is terminating")
+		})
+
 		It("should create NAD in new created namespaces that apply to namespace-selector", func() {
 			testNewNs := f.Namespace.Name + "green"