Gentile started his club career at his father Nando's last team, Juvecaserta Basket, in the LegaDue (Italian 2nd Division).

[1] With Andrea Costa Imola, he caught the eye of Serie A (Italian first division) side Armani Jeans Milano, a club in which his father had previously been a star player.

[2] However, he struggled to get any meaningful playing time, and he then dropped down to the Italian fourth division level, first with Assi Ostuni, and then with Aquila Basket Trento.

With Caserta, he flourished under head coach Stefano Sacripanti, and earned a selection to the 2012–13 Italian All-Star Game, where he played alongside his brother, Alessandro, and he was awarded MVP.

In July 2015, he joined Pallacanestro Reggiana, signing a two-year contract with the club.