Cois is perhaps best known for his spell at Fiorentina (1994–2002) in the mid-late 90s where he won over the fans with his tireless running and tenacious play, becoming important to the side as the less glamorous foil to playmakers like Rui Costa and Domenico Morfeo. With the club he won two Coppa Italia trophies in 1996 and 2001, and a Supercoppa Italiana in 1996, also helping Fiorentina to two third-place finishes in Serie A in 1996 and 1999.