The former Varese boss had been in charge of the Rosanero since June following his work in keeping Siena afloat, and oversaw only three competitive matches, including two consecutive 3-0 defeats to Lazio and Napoli.
He picked up his first point against Cagliari on Sunday, but president Maurizio Zamparini claimed after the match that he'd "rather get drunk" than discuss the trainer's future, casting doubt over their working relationship.
"[The club] announce that Giuseppe Sannino has been dismissed as coach of the first team," read an official club statement.
"We thank him and his coaching staff for their commitment and professionalism shown in recent months."
"At the same time [the club] have given the job to Gian Piero Gasperini, who will lead his first training session with the team on Tuesday afternoon."
Gasperini enjoyed success with Juventus' youth teams, and established Genoa as a Serie A outfit between 2006 and 2010, but his next job ended in failure as he was sacked after just five games at Inter.