This is quite easy to do although it seems many people don’t know about it yet.
Firstly you’ll need an android phone which support OTG functionality which is a feature that allows you to connect USB devices to your phone.
Secondly you should get an OTG cable. Now you have to be careful when getting this because there are some OTG cables out there that don’t support data transfer and are used only for charging other devices, you wouldn’t want to get that. Make sure the one you are getting supports data transfer by testing it with a flash drive.
Thirdly you’ll need to get a pc controller. There are many types out there although i prefer the wireless controllers which are still cheaper than the bluetooth android controllers
Then lastly connect your OTG cable to your phone and then connect your controller USB cable to it and that’s it. Since only a few android games actually support game controllers, you might want to install a PSP emulator on your android device. With this you can play android games almost flawlessly on your device and if you ask me PSP have much better games than Android. ENJOY