diff --git a/extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/WebSocketProcessor.java b/extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/WebSocketProcessor.java
index c367691098caa..4ed22a9985603 100644
--- a/extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/WebSocketProcessor.java
+++ b/extensions/websockets-next/deployment/src/main/java/io/quarkus/websockets/next/deployment/WebSocketProcessor.java
@@ -1065,7 +1065,8 @@ private static ResultHandle uniOnFailureDoOnError(ResultHandle endpointThis, Byt
     private static ResultHandle encodeMessage(ResultHandle endpointThis, BytecodeCreator method, Callback callback,
             GlobalErrorHandlersBuildItem globalErrorHandlers, WebSocketEndpointBuildItem endpoint,
             ResultHandle value) {
-        if (callback.acceptsBinaryMessage()) {
+        if (callback.acceptsBinaryMessage()
+                || isOnOpenWithBinaryReturnType(callback)) {
             // ----------------------
             // === Binary message ===
             // ----------------------
@@ -1119,7 +1120,7 @@ private static ResultHandle encodeMessage(ResultHandle endpointThis, BytecodeCre
                         value,
                         fun.getInstance());
             } else {
-                // return sendBinary(buffer,broadcast);
+                // return sendBinary(encodeBuffer(b),broadcast);
                 ResultHandle buffer = encodeBuffer(method, callback.returnType(), value, endpointThis, callback);
                 return method.invokeVirtualMethod(MethodDescriptor.ofMethod(WebSocketEndpointBase.class,
                         "sendBinary", Uni.class, Buffer.class, boolean.class), endpointThis, buffer,
@@ -1407,4 +1408,16 @@ static boolean isByteArray(Type type) {
     static String methodToString(MethodInfo method) {
         return method.declaringClass().name() + "#" + method.name() + "()";
     }
+
+    private static boolean isOnOpenWithBinaryReturnType(Callback callback) {
+        if (callback.isOnOpen()) {
+            Type returnType = callback.returnType();
+            if (callback.isReturnTypeUni() || callback.isReturnTypeMulti()) {
+                returnType = callback.returnType().asParameterizedType().arguments().get(0);
+            }
+            return WebSocketDotNames.BUFFER.equals(returnType.name())
+                    || (returnType.kind() == Kind.ARRAY && PrimitiveType.BYTE.equals(returnType.asArrayType().constituent()));
+        }
+        return false;
+    }
 }
diff --git a/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/onopenreturntypes/OnOpenReturnTypesTest.java b/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/onopenreturntypes/OnOpenReturnTypesTest.java
new file mode 100644
index 0000000000000..aa5ab58469ab9
--- /dev/null
+++ b/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/onopenreturntypes/OnOpenReturnTypesTest.java
@@ -0,0 +1,71 @@
+package io.quarkus.websockets.next.test.onopenreturntypes;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.net.URI;
+
+import jakarta.inject.Inject;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+import io.quarkus.test.common.http.TestHTTPResource;
+import io.quarkus.websockets.next.OnOpen;
+import io.quarkus.websockets.next.WebSocket;
+import io.quarkus.websockets.next.WebSocketConnection;
+import io.quarkus.websockets.next.test.utils.WSClient;
+import io.quarkus.websockets.next.test.utils.WSClient.ReceiverMode;
+import io.vertx.core.Vertx;
+import io.vertx.core.buffer.Buffer;
+
+public class OnOpenReturnTypesTest {
+
+    @RegisterExtension
+    public static final QuarkusUnitTest test = new QuarkusUnitTest()
+            .withApplicationRoot(root -> {
+                root.addClasses(EndpointText.class, EndpointBinary.class, WSClient.class);
+            });
+
+    @Inject
+    Vertx vertx;
+
+    @TestHTTPResource("end-text")
+    URI endText;
+
+    @TestHTTPResource("end-binary")
+    URI endBinary;
+
+    @Test
+    void testReturnTypes() throws Exception {
+        try (WSClient textClient = WSClient.create(vertx, ReceiverMode.TEXT).connect(endText)) {
+            textClient.waitForMessages(1);
+            assertEquals("/end-text", textClient.getMessages().get(0).toString());
+        }
+        try (WSClient binaryClient = WSClient.create(vertx, ReceiverMode.BINARY).connect(endBinary)) {
+            binaryClient.waitForMessages(1);
+            assertEquals("/end-binary", binaryClient.getMessages().get(0).toString());
+        }
+    }
+
+    @WebSocket(path = "/end-text")
+    public static class EndpointText {
+
+        @OnOpen
+        String open(WebSocketConnection connection) {
+            return connection.handshakeRequest().path();
+        }
+
+    }
+
+    @WebSocket(path = "/end-binary")
+    public static class EndpointBinary {
+
+        @OnOpen
+        Buffer open(WebSocketConnection connection) {
+            return Buffer.buffer(connection.handshakeRequest().path());
+        }
+
+    }
+
+}
diff --git a/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/utils/WSClient.java b/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/utils/WSClient.java
index 955eb9c1b315c..2f1974089db90 100644
--- a/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/utils/WSClient.java
+++ b/extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/utils/WSClient.java
@@ -17,16 +17,26 @@
 
 public class WSClient implements AutoCloseable {
 
+    public static WSClient create(Vertx vertx) {
+        return new WSClient(vertx);
+    }
+
+    public static WSClient create(Vertx vertx, ReceiverMode mode) {
+        return new WSClient(vertx, mode);
+    }
+
     private final WebSocketClient client;
     private AtomicReference<WebSocket> socket = new AtomicReference<>();
     private List<Buffer> messages = new CopyOnWriteArrayList<>();
+    private final ReceiverMode mode;
 
-    public WSClient(Vertx vertx) {
+    public WSClient(Vertx vertx, ReceiverMode mode) {
         this.client = vertx.createWebSocketClient();
+        this.mode = mode;
     }
 
-    public static WSClient create(Vertx vertx) {
-        return new WSClient(vertx);
+    public WSClient(Vertx vertx) {
+        this(vertx, ReceiverMode.ALL);
     }
 
     public static URI toWS(URI uri, String path) {
@@ -52,7 +62,19 @@ public WSClient connect(WebSocketConnectOptions options, URI url) {
             uri.append("?").append(url.getQuery());
         }
         ClientWebSocket webSocket = client.webSocket();
-        webSocket.handler(b -> messages.add(b));
+        switch (mode) {
+            case ALL:
+                webSocket.handler(b -> messages.add(b));
+                break;
+            case BINARY:
+                webSocket.binaryMessageHandler(b -> messages.add(b));
+                break;
+            case TEXT:
+                webSocket.textMessageHandler(b -> messages.add(Buffer.buffer(b)));
+                break;
+            default:
+                throw new IllegalStateException();
+        }
         await(webSocket.connect(options.setPort(url.getPort()).setHost(url.getHost()).setURI(uri.toString())));
         var prev = socket.getAndSet(webSocket);
         if (prev != null) {
@@ -135,4 +157,10 @@ public void close() {
         disconnect();
     }
 
+    public enum ReceiverMode {
+        BINARY,
+        TEXT,
+        ALL
+    }
+
 }