In 2002, Riganò joined Florentia Viola of Serie C2, and scored a personal record of 30 goals in 32 matches, earning the title of top-scorer in the league once again and helping Fiorentina to obtain promotion. During the 2003–04 season, he scored 23 Serie B goals in 44 matches, helping Fiorentina to win promotion to Serie A and earning his Serie A debut at the age of 30 the following season. During the 2005–06 winter transfer window, he was loaned to Empoli with little success.