Since Pycharm recently had updates, my case was slightly different since I installed pyinstaller from the interpreter settings, as shown in the following figure:

For Linux users :
You can install it in both Python 2.7 and Python 3.7+ . Make sure that the pyinstaller found the path to the pyinstaller pyinstaller Then, in the "Settings" parameter, find "Tools โ External Tools" and add a new external tool, as shown in the following figure: 
For Windows users :
If you are using Pycharm or any virtual environment. Unfortunately, Pycharm creates its local vertical environment on the venv path only you specify an interpreter . So you have to install the external tool (pyinstaller) on the real path of your python 3.7.exe, as shown in the picture 
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