I'm trying to do the same thing and it does not work for me. My test code does not find the "append(jsobject)" method, in my case the append method is show as "append(QQmlV4Function*)" and the QQmlV4Function type is a private Qt type so I can't invoke the method. Can provide more details on how you implemented this? What arguments are you passing on Q_ARG(blah blah)? What version of Qt are you using? Thanks.