@Josef-Lintz said in Undefined reference in app which includes library:
and rename my library to something else, I can't run my app anymore because the app can't find its dependency.
Correct.
If I build the app using QT creator, there's no ".so" file in the build directory, and it runs fine.
Then it finds it somewhere else, perhaps in your project or whatever. There is LD_LIBRARY_PATH environment variable, that might be relevant.
Does QT embed ".so" files in the executable?
No. And Qt does not "do anything" anyway. Creator is just building using make etc., anything to do with that is external to Qt.