How can I say "Got it!" in Italian? Google Translate gives "Fatto!" and "Ce l'ho!", but I think these are not correct answers.
It depends on the context.
"Ce l'ho" may be correct, as in the example from Narmer, if it means that you possess something.
When it means that you understood something, as black and Elisabetta said, you can translate:
"OK" "Capito" "Chiaro" "Va bene"
In the latter case the use of "Ce l'ho" is quite uncommon...
I agree that it highly depends on the meaning, and when it means that you understood something, especially if it's not said in response to a question but after doing some thinking - in my opinion the best translation is "Ci sono!" ("I'm there / I got there!") as suggested by @laika because it is of common use and it is as informal as "I got it!". I'm from the north as well (Emilia Romagna) but "Ce l'ho!" in my experience is not common at all, personally I believe it's regional.