diff --git a/compos/compos_key_cmd/compos_key_cmd.cpp b/compos/compos_key_cmd/compos_key_cmd.cpp
index a194b95..874a208 100644
--- a/compos/compos_key_cmd/compos_key_cmd.cpp
+++ b/compos/compos_key_cmd/compos_key_cmd.cpp
@@ -112,6 +112,11 @@
         return ScopedAStatus::ok();
     }
 
+    ::ndk::ScopedAStatus onPayloadReady(int32_t in_cid) override {
+        LOG(INFO) << "Payload is ready! cid = " << in_cid;
+        return ScopedAStatus::ok();
+    }
+
     ::ndk::ScopedAStatus onPayloadFinished(int32_t in_cid, int32_t in_exit_code) override {
         LOG(INFO) << "Payload finished! cid = " << in_cid << ", exit_code = " << in_exit_code;
         return ScopedAStatus::ok();
diff --git a/demo/java/com/android/microdroid/demo/MainActivity.java b/demo/java/com/android/microdroid/demo/MainActivity.java
index ea071cb..6a46f73 100644
--- a/demo/java/com/android/microdroid/demo/MainActivity.java
+++ b/demo/java/com/android/microdroid/demo/MainActivity.java
@@ -176,6 +176,14 @@
                         }
 
                         @Override
+                        public void onPayloadReady(VirtualMachine vm) {
+                            // This check doesn't 100% prevent race condition, but is fine for demo.
+                            if (!mService.isShutdown()) {
+                                mPayloadOutput.postValue("(Payload is ready)");
+                            }
+                        }
+
+                        @Override
                         public void onPayloadFinished(VirtualMachine vm, int exitCode) {
                             // This check doesn't 100% prevent race condition, but is fine for demo.
                             if (!mService.isShutdown()) {
diff --git a/javalib/src/android/system/virtualmachine/VirtualMachine.java b/javalib/src/android/system/virtualmachine/VirtualMachine.java
index f077f54..f4ac467 100644
--- a/javalib/src/android/system/virtualmachine/VirtualMachine.java
+++ b/javalib/src/android/system/virtualmachine/VirtualMachine.java
@@ -303,6 +303,15 @@
                         }
 
                         @Override
+                        public void onPayloadReady(int cid) {
+                            final VirtualMachineCallback cb = mCallback;
+                            if (cb == null) {
+                                return;
+                            }
+                            cb.onPayloadReady(VirtualMachine.this);
+                        }
+
+                        @Override
                         public void onPayloadFinished(int cid, int exitCode) {
                             final VirtualMachineCallback cb = mCallback;
                             if (cb == null) {
diff --git a/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java b/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
index 96986bc..988acd7 100644
--- a/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
+++ b/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
@@ -31,6 +31,9 @@
     /** Called when the payload starts in the VM. */
     void onPayloadStarted(@NonNull VirtualMachine vm, @Nullable ParcelFileDescriptor stream);
 
+    /** Called when the payload in the VM is ready to serve. */
+    void onPayloadReady(@NonNull VirtualMachine vm);
+
     /** Called when the payload has finished in the VM. */
     void onPayloadFinished(@NonNull VirtualMachine vm, int exitCode);
 
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
index 4dc4333..15354a3 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
@@ -32,6 +32,11 @@
     void onPayloadStarted(int cid, in @nullable ParcelFileDescriptor stream);
 
     /**
+     * Called when the payload in the VM is ready to serve.
+     */
+    void onPayloadReady(int cid);
+
+    /**
      * Called when the payload has finished in the VM. `exitCode` is the exit code of the payload.
      */
     void onPayloadFinished(int cid, int exitCode);
diff --git a/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl b/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
index 730f6c2..10b14e0 100644
--- a/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
+++ b/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
@@ -24,6 +24,12 @@
     void notifyPayloadStarted(int cid);
 
     /**
+     * Notifies that the payload is ready to serve.
+     * TODO(b/191845268): remove cid parameter
+     */
+    void notifyPayloadReady(int cid);
+
+    /**
      * Notifies that the payload has finished.
      * TODO(b/191845268): remove cid parameter
      */
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index 562843b..6b60da3 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -640,6 +640,16 @@
         }
     }
 
+    /// Call all registered callbacks to notify that the payload is ready to serve.
+    pub fn notify_payload_ready(&self, cid: Cid) {
+        let callbacks = &*self.0.lock().unwrap();
+        for callback in callbacks {
+            if let Err(e) = callback.onPayloadReady(cid as i32) {
+                error!("Error notifying payload ready event from VM CID {}: {}", cid, e);
+            }
+        }
+    }
+
     /// Call all registered callbacks to notify that the payload has finished.
     pub fn notify_payload_finished(&self, cid: Cid, exit_code: i32) {
         let callbacks = &*self.0.lock().unwrap();
@@ -799,6 +809,21 @@
         }
     }
 
+    fn notifyPayloadReady(&self, cid: i32) -> binder::Result<()> {
+        let cid = cid as Cid;
+        if let Some(vm) = self.state.lock().unwrap().get_vm(cid) {
+            info!("VM having CID {} payload is ready", cid);
+            vm.callbacks.notify_payload_ready(cid);
+            Ok(())
+        } else {
+            error!("notifyPayloadReady is called from an unknown cid {}", cid);
+            Err(new_binder_exception(
+                ExceptionCode::SERVICE_SPECIFIC,
+                format!("cannot find a VM with cid {}", cid),
+            ))
+        }
+    }
+
     fn notifyPayloadFinished(&self, cid: i32, exit_code: i32) -> binder::Result<()> {
         let cid = cid as Cid;
         if let Some(vm) = self.state.lock().unwrap().get_vm(cid) {
diff --git a/vm/src/run.rs b/vm/src/run.rs
index 825fdeb..4b656ae 100644
--- a/vm/src/run.rs
+++ b/vm/src/run.rs
@@ -189,6 +189,10 @@
         Ok(())
     }
 
+    fn onPayloadReady(&self, _cid: i32) -> BinderResult<()> {
+        Ok(())
+    }
+
     fn onPayloadFinished(&self, _cid: i32, _exit_code: i32) -> BinderResult<()> {
         Ok(())
     }