diff --git a/artifacts/flagger/crd.yaml b/artifacts/flagger/crd.yaml
index 19b24319..9f93d4ea 100644
--- a/artifacts/flagger/crd.yaml
+++ b/artifacts/flagger/crd.yaml
@@ -158,6 +158,9 @@ spec:
                     portName:
                       description: Container port name
                       type: string
+                    appProtocol:
+                      description: Application protocol of the port
+                      type: string
                     targetPort:
                       description: Container target port name
                       x-kubernetes-int-or-string: true
diff --git a/docs/gitbook/usage/how-it-works.md b/docs/gitbook/usage/how-it-works.md
index 58a5802f..45fb5d9e 100644
--- a/docs/gitbook/usage/how-it-works.md
+++ b/docs/gitbook/usage/how-it-works.md
@@ -134,6 +134,7 @@ spec:
     name: podinfo
     port: 9898
     portName: http
+    appProtocol: http
     targetPort: 9898
     portDiscovery: true
 ```
@@ -142,6 +143,7 @@ The container port from the target workload should match the `service.port` or `
 The `service.name` is optional, defaults to `spec.targetRef.name`.
 The `service.targetPort` can be a container port number or name.
 The `service.portName` is optional (defaults to `http`), if your workload uses gRPC then set the port name to `grpc`.
+The `service.appProtocol` is optional, more details can be found [here](https://kubernetes.io/docs/concepts/services-networking/service/#application-protocol).
 
 If port discovery is enabled, Flagger scans the target workload and extracts the containers ports
 excluding the port specified in the canary service and service mesh sidecar ports.
diff --git a/pkg/apis/flagger/v1beta1/canary.go b/pkg/apis/flagger/v1beta1/canary.go
index 13a45a10..f56916fb 100644
--- a/pkg/apis/flagger/v1beta1/canary.go
+++ b/pkg/apis/flagger/v1beta1/canary.go
@@ -128,6 +128,11 @@ type CanaryService struct {
 	// +optional
 	TargetPort intstr.IntOrString `json:"targetPort,omitempty"`
 
+	// AppProtocol of the service
+	// https://kubernetes.io/docs/concepts/services-networking/service/#application-protocol
+	// +optional
+	AppProtocol string `json:"appProtocol,omitempty"`
+
 	// PortDiscovery adds all container ports to the generated Kubernetes service
 	PortDiscovery bool `json:"portDiscovery"`
 
diff --git a/pkg/router/kubernetes_default.go b/pkg/router/kubernetes_default.go
index 118d5ab0..61ffd7fd 100644
--- a/pkg/router/kubernetes_default.go
+++ b/pkg/router/kubernetes_default.go
@@ -114,6 +114,10 @@ func (c *KubernetesDefaultRouter) reconcileService(canary *flaggerv1.Canary, nam
 		},
 	}
 
+	if v := canary.Spec.Service.AppProtocol; v != "" {
+		svcSpec.Ports[0].AppProtocol = &v
+	}
+
 	// set additional ports
 	for n, p := range c.ports {
 		cp := corev1.ServicePort{
diff --git a/pkg/router/kubernetes_default_test.go b/pkg/router/kubernetes_default_test.go
index a1888341..9d4648f6 100644
--- a/pkg/router/kubernetes_default_test.go
+++ b/pkg/router/kubernetes_default_test.go
@@ -39,6 +39,7 @@ func TestServiceRouter_Create(t *testing.T) {
 		flaggerClient: mocks.flaggerClient,
 		logger:        mocks.logger,
 	}
+	appProtocol := "http"
 
 	err := router.Initialize(mocks.canary)
 	require.NoError(t, err)
@@ -49,6 +50,7 @@ func TestServiceRouter_Create(t *testing.T) {
 	canarySvc, err := mocks.kubeClient.CoreV1().Services("default").Get(context.TODO(), "podinfo-canary", metav1.GetOptions{})
 	require.NoError(t, err)
 
+	assert.Equal(t, &appProtocol, canarySvc.Spec.Ports[0].AppProtocol)
 	assert.Equal(t, "http", canarySvc.Spec.Ports[0].Name)
 	assert.Equal(t, int32(9898), canarySvc.Spec.Ports[0].Port)
 
diff --git a/pkg/router/router_test.go b/pkg/router/router_test.go
index 9f52cbc1..fdf33530 100644
--- a/pkg/router/router_test.go
+++ b/pkg/router/router_test.go
@@ -100,6 +100,7 @@ func newTestCanary() *flaggerv1.Canary {
 			Service: flaggerv1.CanaryService{
 				Port:          9898,
 				PortDiscovery: true,
+				AppProtocol:   "http",
 				Headers: &istiov1alpha3.Headers{
 					Request: &istiov1alpha3.HeaderOperations{
 						Add: map[string]string{