The flamboyant attacker has decided to leave the Nerazzurri after just one season and will continue his career with the Stadio Ennio Tardini side.
Both sides had long been in talks over the 30-year-old and Parma revealed on its official club website on Wednesday that a deal has been completed.
Cassano will be wearing the No.99 jersey at his new club.
The attacker was at Inter for only one season after joining the club from AC Milan in the summer of 2012 in a deal that saw Giampaolo Pazzini head to the Rossoneri.
Cassano netted seven goals in 28 Serie A appearances for the Giuseppe Meazza side last season, but he was not part of new head coach Walter Mazzarri's plans for the future.
He previously played for the likes of Bari, Roma, Real Madrid and Sampdoria.
The forward will be unveiled to the press on Thursday.