diff --git a/pkg/kthena-router/webhook/validator.go b/pkg/kthena-router/webhook/validator.go
index 04b803c31..81e7e92ff 100644
--- a/pkg/kthena-router/webhook/validator.go
+++ b/pkg/kthena-router/webhook/validator.go
@@ -180,6 +180,16 @@ func (v *KthenaRouterValidator) validateModelRoute(modelRoute *networkingv1alpha
 		if len(rule.TargetModels) == 0 {
 			allErrs = append(allErrs, field.Required(ruleField.Child("targetModels"), "each rule must have at least one target model"))
 		}
+		for j, target := range rule.TargetModels {
+			targetField := ruleField.Child("targetModels").Index(j)
+			if target == nil {
+				allErrs = append(allErrs, field.Invalid(targetField, target, "target model must not be nil"))
+				continue
+			}
+			if target.ModelServerName == "" {
+				allErrs = append(allErrs, field.Required(targetField.Child("modelServerName"), "modelServerName must not be empty"))
+			}
+		}
 	}
 
 	if len(allErrs) > 0 {
diff --git a/pkg/kthena-router/webhook/validator_test.go b/pkg/kthena-router/webhook/validator_test.go
index 855beb303..9747c953e 100644
--- a/pkg/kthena-router/webhook/validator_test.go
+++ b/pkg/kthena-router/webhook/validator_test.go
@@ -330,6 +330,88 @@ func TestValidateModelRoute(t *testing.T) {
 			expectValid:    false,
 			expectedReason: "validation failed:   - spec.rules[0]: Invalid value: null: rule must not be nil",
 		},
+		{
+			name: "invalid model route - targetModel with empty modelServerName",
+			modelRoute: &networkingv1alpha1.ModelRoute{
+				TypeMeta: metav1.TypeMeta{
+					APIVersion: "networking.serving.volcano.sh/v1alpha1",
+					Kind:       "ModelRoute",
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "test-route",
+					Namespace: "default",
+				},
+				Spec: networkingv1alpha1.ModelRouteSpec{
+					ModelName: "test-model",
+					Rules: []*networkingv1alpha1.Rule{
+						{
+							Name: "test-rule",
+							TargetModels: []*networkingv1alpha1.TargetModel{
+								{
+									ModelServerName: "",
+								},
+							},
+						},
+					},
+				},
+			},
+			expectValid:    false,
+			expectedReason: "validation failed:   - spec.rules[0].targetModels[0].modelServerName: Required value: modelServerName must not be empty",
+		},
+		{
+			name: "invalid model route - nil target model entry",
+			modelRoute: &networkingv1alpha1.ModelRoute{
+				TypeMeta: metav1.TypeMeta{
+					APIVersion: "networking.serving.volcano.sh/v1alpha1",
+					Kind:       "ModelRoute",
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "test-route",
+					Namespace: "default",
+				},
+				Spec: networkingv1alpha1.ModelRouteSpec{
+					ModelName: "test-model",
+					Rules: []*networkingv1alpha1.Rule{
+						{
+							Name: "test-rule",
+							TargetModels: []*networkingv1alpha1.TargetModel{
+								nil,
+							},
+						},
+					},
+				},
+			},
+			expectValid:    false,
+			expectedReason: "validation failed:   - spec.rules[0].targetModels[0]: Invalid value: null: target model must not be nil",
+		},
+		{
+			name: "invalid model route - mixed valid and invalid targetModels",
+			modelRoute: &networkingv1alpha1.ModelRoute{
+				TypeMeta: metav1.TypeMeta{
+					APIVersion: "networking.serving.volcano.sh/v1alpha1",
+					Kind:       "ModelRoute",
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "test-route",
+					Namespace: "default",
+				},
+				Spec: networkingv1alpha1.ModelRouteSpec{
+					ModelName: "test-model",
+					Rules: []*networkingv1alpha1.Rule{
+						{
+							Name: "test-rule",
+							TargetModels: []*networkingv1alpha1.TargetModel{
+								{ModelServerName: "valid-server"},
+								{ModelServerName: ""},
+								nil,
+							},
+						},
+					},
+				},
+			},
+			expectValid:    false,
+			expectedReason: "validation failed:   - spec.rules[0].targetModels[1].modelServerName: Required value: modelServerName must not be empty  - spec.rules[0].targetModels[2]: Invalid value: null: target model must not be nil",
+		},
 		{
 			name: "invalid model route - combined errors: missing model name and empty targetModels",
 			modelRoute: &networkingv1alpha1.ModelRoute{