Parma bring in Cassani from Fiorentina
The former Italy international spent last season on loan at the Stadio Ennio Tardini, featuring 38 times in all competitions.
Having helped the club finish sixth, he completed a permanent move to Parma on Monday - agreeing a deal that will keep him under contract until 2017.
"Parma FC announces that it has acquired outright ACF Fiorentina defender Mattia Cassani," read a statement from the club.
"Mattia, among the protagonists of the extraordinary 2013/2014 season which saw our team finish in sixth place, is available to [coach] Roberto Donadoni and has signed a three-year contract."
Cassani began his career at Juventus before enjoying permanent stints at Verona, Palermo and Fiorentina.
Parma have endured a difficult close-season, with president Tommaso Ghirardi announcing his intention to sell the club following a row over their UEFA license.
Despite that uncertainty, the club have managed to bring in Jonathan Biabiany outright from Sampdoria and now Cassani.