Medzhidov got the better of the early exchanges, opening up a 6-4 lead at the end of the first round.
However, the Italian responded well and levelled matters at 10-10 heading into the final round.
Cammarelle found the target with a big left hand early in the third, which sent the Azeri stumbling backwards.
Medzhidov was now struggling to hold Cammarelle off and was on the receiving end of a few decent punches.
The Italian was in the driving seat in the final round and he went on to win by a 13-12 scoreline.