Do I need JNI for my C++ library when deploying to Android?

[anda_skoa]

Now, when I want to switch kits to Android and deploy it to Android, then I would need to recompile my .so library file for Android architecture. My question is, do I need to create a JNI wrapper for my external library for it to be used with my Qt Creator application on Android?

I would think this depends in the language the application is using. If the application is using C++ then it can obviously direclty link against any C++ library.
If the application is being written in Java, it will need some bridge code to link to the library.

Also, forget about my library for a moment, to help me understand it better, under the covers, is Qt using JNI to call its libraries?

Not sure what you mean, Qt is "the libraries".

Cheers,
_