diff --git a/clients/command-pubsub/src/main/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumer.java b/clients/command-pubsub/src/main/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumer.java
index 8eea206c9a..966c3372ff 100644
--- a/clients/command-pubsub/src/main/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumer.java
+++ b/clients/command-pubsub/src/main/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumer.java
@@ -204,10 +204,11 @@ public Future<Void> start() {
     }
 
     private void createReceiver() {
-        receiver = (PubsubMessage message, AckReplyConsumer consumer) -> handleCommandMessage(message);
+        receiver = this::handleCommandMessage;
     }
 
-    Future<Void> handleCommandMessage(final PubsubMessage message) {
+    Future<Void> handleCommandMessage(final PubsubMessage message, final AckReplyConsumer consumer) {
+        consumer.ack();
         final PubSubBasedCommand command;
         try {
             command = PubSubBasedCommand.fromRoutedCommandMessage(message);
diff --git a/clients/command-pubsub/src/test/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumerTest.java b/clients/command-pubsub/src/test/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumerTest.java
index 03db73bcd9..98b4ff625a 100644
--- a/clients/command-pubsub/src/test/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumerTest.java
+++ b/clients/command-pubsub/src/test/java/org/eclipse/hono/client/command/pubsub/PubSubBasedInternalCommandConsumerTest.java
@@ -17,6 +17,7 @@
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
@@ -51,6 +52,7 @@
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
 import com.google.cloud.pubsub.v1.MessageReceiver;
 import com.google.pubsub.v1.PubsubMessage;
 
@@ -81,6 +83,8 @@ public class PubSubBasedInternalCommandConsumerTest {
 
     private TenantClient tenantClient;
 
+    private AckReplyConsumer ackReplyConsumer;
+
     private PubSubBasedInternalCommandConsumer internalCommandConsumer;
 
     @BeforeEach
@@ -91,6 +95,9 @@ void setUp() {
         final Tracer tracer = TracingMockSupport.mockTracer(TracingMockSupport.mockSpan());
         commandHandlers = new CommandHandlers();
         tenantClient = mock(TenantClient.class);
+        ackReplyConsumer = mock(AckReplyConsumer.class);
+
+        doNothing().when(ackReplyConsumer).ack();
 
         doAnswer(invocation -> {
             final String tenantId = invocation.getArgument(0);
@@ -109,7 +116,7 @@ void setUp() {
                 .thenReturn(Future.succeededFuture(topicAndSubscription));
         when(adminClientManager
                 .getOrCreateSubscription(CommandConstants.INTERNAL_COMMAND_ENDPOINT, adapterInstanceId))
-                        .thenReturn(Future.succeededFuture(topicAndSubscription));
+                .thenReturn(Future.succeededFuture(topicAndSubscription));
 
         subscriber = mock(PubSubSubscriberClient.class);
         when(subscriber.subscribe(true)).thenReturn(Future.succeededFuture());
@@ -156,7 +163,8 @@ public void testHandleCommandMessageSendErrorResponse() {
                 Future.failedFuture(
                         StatusCodeMapper.from(HttpURLConnection.HTTP_UNAVAILABLE, "failed to retrieve tenant")));
 
-        internalCommandConsumer.handleCommandMessage(message);
+        internalCommandConsumer.handleCommandMessage(message, ackReplyConsumer);
+        verify(ackReplyConsumer).ack();
         verify(commandHandler, never()).apply(any(PubSubBasedCommandContext.class));
         verify(commandResponseSender).sendCommandResponse(
                 argThat(t -> t.getTenantId().equals(tenantId)),
@@ -166,7 +174,8 @@ public void testHandleCommandMessageSendErrorResponse() {
     }
 
     /**
-     * Verifies that the consumer handles an invalid command message with missing subject by invoking the matching handler.
+     * Verifies that the consumer handles an invalid command message with missing subject by invoking the matching
+     * handler.
      */
     @Test
     public void testHandleCommandMessageWithInvalidAttribute() {
@@ -175,10 +184,11 @@ public void testHandleCommandMessageWithInvalidAttribute() {
         final Context context = VertxMockSupport.mockContext(mock(Vertx.class));
         commandHandlers.putCommandHandler(tenantId, deviceId, null, commandHandler, context);
 
-        internalCommandConsumer.handleCommandMessage(message);
+        internalCommandConsumer.handleCommandMessage(message, ackReplyConsumer);
 
         final ArgumentCaptor<CommandContext> commandContextArgumentCaptor = ArgumentCaptor
                 .forClass(CommandContext.class);
+        verify(ackReplyConsumer).ack();
         verify(commandHandler).apply(commandContextArgumentCaptor.capture());
         assertThat(commandContextArgumentCaptor.getValue()).isNotNull();
         assertThat(commandContextArgumentCaptor.getValue().getCommand().isValid()).isFalse();
@@ -196,10 +206,11 @@ public void testHandleCommandMessageWithHandlerForDevice() {
         final Context context = VertxMockSupport.mockContext(mock(Vertx.class));
         commandHandlers.putCommandHandler(tenantId, deviceId, null, commandHandler, context);
 
-        internalCommandConsumer.handleCommandMessage(message);
+        internalCommandConsumer.handleCommandMessage(message, ackReplyConsumer);
 
         final ArgumentCaptor<CommandContext> commandContextArgumentCaptor = ArgumentCaptor
                 .forClass(CommandContext.class);
+        verify(ackReplyConsumer).ack();
         verify(commandHandler).apply(commandContextArgumentCaptor.capture());
         assertThat(commandContextArgumentCaptor.getValue()).isNotNull();
         assertThat(commandContextArgumentCaptor.getValue().getCommand().isValid()).isTrue();
@@ -213,7 +224,8 @@ public void testHandleCommandMessageWithNoHandlerForDevice() {
         final PubsubMessage message = getPubSubMessage(subject, "true");
         final Function<CommandContext, Future<Void>> commandHandler = mock(Function.class);
 
-        internalCommandConsumer.handleCommandMessage(message);
+        internalCommandConsumer.handleCommandMessage(message, ackReplyConsumer);
+        verify(ackReplyConsumer).ack();
         verify(commandHandler, never()).apply(any(PubSubBasedCommandContext.class));
         verify(commandResponseSender).sendCommandResponse(
                 argThat(t -> t.getTenantId().equals(tenantId)),
@@ -223,8 +235,8 @@ public void testHandleCommandMessageWithNoHandlerForDevice() {
     }
 
     /**
-     * Verifies that a failed future is returned if an IllegalArgumentException is thrown when no command can be
-     * created by the PubSubMessage.
+     * Verifies that a failed future is returned if an IllegalArgumentException is thrown when no command can be created
+     * by the PubSubMessage.
      */
     @Test
     public void testHandleCommandMessageFailedWhenMessageContainsNoAttributes() {
@@ -233,8 +245,9 @@ public void testHandleCommandMessageFailedWhenMessageContainsNoAttributes() {
         final Context context = VertxMockSupport.mockContext(mock(Vertx.class));
         commandHandlers.putCommandHandler(tenantId, deviceId, null, commandHandler, context);
 
-        final Future<Void> result = internalCommandConsumer.handleCommandMessage(message);
+        final Future<Void> result = internalCommandConsumer.handleCommandMessage(message, ackReplyConsumer);
         assertThat(result.failed()).isTrue();
+        verify(ackReplyConsumer).ack();
     }
 
     private PubsubMessage getPubSubMessage(final String subject, final String responseRequired) {
@@ -246,7 +259,8 @@ private PubsubMessage getPubSubMessage(final String subject, final String respon
         Optional.ofNullable(subject)
                 .ifPresent(ok -> attributes.put(MessageHelper.SYS_PROPERTY_SUBJECT, subject));
         Optional.ofNullable(responseRequired)
-                .ifPresent(ok -> attributes.put(PubSubMessageHelper.PUBSUB_PROPERTY_RESPONSE_REQUIRED, responseRequired));
+                .ifPresent(
+                        ok -> attributes.put(PubSubMessageHelper.PUBSUB_PROPERTY_RESPONSE_REQUIRED, responseRequired));
 
         return PubsubMessage.newBuilder().putAllAttributes(attributes).build();
     }