diff --git a/api/runtime/v1/sandbox-api.pb.go b/api/runtime/v1/sandbox-api.pb.go
index 9c93c32..55bef6a 100644
--- a/api/runtime/v1/sandbox-api.pb.go
+++ b/api/runtime/v1/sandbox-api.pb.go
@@ -1609,7 +1609,9 @@ type StartResponse struct {
 	// Message contains details about the start result.
 	Message string `protobuf:"bytes,2,opt,name=message,proto3" json:"message,omitempty"`
 	// ID is the unique sandbox ID.
-	ID            string `protobuf:"bytes,3,opt,name=id,proto3" json:"id,omitempty"`
+	ID string `protobuf:"bytes,3,opt,name=id,proto3" json:"id,omitempty"`
+	// SandboxIP is the address assigned to the sandbox network endpoint.
+	SandboxIp     string `protobuf:"bytes,4,opt,name=sandbox_ip,json=sandboxIp,proto3" json:"sandbox_ip,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -1665,6 +1667,13 @@ func (x *StartResponse) GetID() string {
 	return ""
 }
 
+func (x *StartResponse) GetSandboxIp() string {
+	if x != nil {
+		return x.SandboxIp
+	}
+	return ""
+}
+
 // CheckpointRequest describes a synchronous checkpoint operation.
 type CheckpointRequest struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
@@ -3062,11 +3071,13 @@ const file_api_runtime_v1_sandbox_api_proto_rawDesc = "" +
 	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\x1a?\n" +
 	"\x11MetricLabelsEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"M\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"l\n" +
 	"\rStartResponse\x12\x12\n" +
 	"\x04code\x18\x01 \x01(\x05R\x04code\x12\x18\n" +
 	"\amessage\x18\x02 \x01(\tR\amessage\x12\x0e\n" +
-	"\x02id\x18\x03 \x01(\tR\x02id\"\xd9\x01\n" +
+	"\x02id\x18\x03 \x01(\tR\x02id\x12\x1d\n" +
+	"\n" +
+	"sandbox_ip\x18\x04 \x01(\tR\tsandboxIp\"\xd9\x01\n" +
 	"\x11CheckpointRequest\x12\x0e\n" +
 	"\x02id\x18\x01 \x01(\tR\x02id\x12%\n" +
 	"\x0echeckpoint_dir\x18\x02 \x01(\tR\rcheckpointDir\x12'\n" +
diff --git a/api/runtime/v1/sandbox-api.proto b/api/runtime/v1/sandbox-api.proto
index 22b96d9..f6f45bb 100644
--- a/api/runtime/v1/sandbox-api.proto
+++ b/api/runtime/v1/sandbox-api.proto
@@ -283,6 +283,8 @@ message StartResponse {
   string message = 2;
   // ID is the unique sandbox ID.
   string id = 3;
+  // SandboxIP is the address assigned to the sandbox network endpoint.
+  string sandbox_ip = 4;
 }
 
 // CheckpointRequest describes a synchronous checkpoint operation.
diff --git a/api/runtime/v1/sandbox_api_compat_test.go b/api/runtime/v1/sandbox_api_compat_test.go
index 25390e5..960f4cc 100644
--- a/api/runtime/v1/sandbox_api_compat_test.go
+++ b/api/runtime/v1/sandbox_api_compat_test.go
@@ -36,7 +36,7 @@ func TestV010WireContract(t *testing.T) {
 	// Rolled for StartRequest.inject_entrypoint (field 22), which supplies the
 	// in-sandbox destination for injected OCI image startup configuration.
 	// Recompute after any proto change: run this test, copy the got hash.
-	const want = "5cbcd4bbad5035b8c2d5224e0f08944f38ee0188d5116e09ac8f16ef5419fc6b"
+	const want = "21eb701d4c16828d5f4ac42d6a50d6f644e038b6b967b4c5165a9dd025aed67b"
 	if got := hex.EncodeToString(sum[:]); got != want {
 		t.Fatalf("sandbox API descriptor hash = %s, want %s", got, want)
 	}
diff --git a/internal/server/server.go b/internal/server/server.go
index 66ecaa5..61d24db 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -1637,9 +1637,10 @@ func (h *sandboxService) Start(ctx context.Context, request *runtime.StartReques
 	})
 	startSucceeded = true
 	return &runtime.StartResponse{
-		Code:    0,
-		Message: "Succeed",
-		ID:      sandboxID,
+		Code:      0,
+		Message:   "Succeed",
+		ID:        sandboxID,
+		SandboxIp: preparedResources.sandboxIP,
 	}, nil
 }