Giuseppe Rossi made his move from Villarreal to Fiorentina official on Monday after the two sides had come to an agreement last week.
Rossi has been out of action since October 2011 after two separate operations on his right knee, but he expressed his excitement over being a part of his new team.
"I like the Viola project, a lot. I want to be a part of it," Rossi said. "There are many youngsters here, but also players of experience and we all know that Fiorentina are playing the best football in Italy. I can't wait to start playing alongside Stevan Jovetic and Luca Toni, great players."
The 25-year-old moved to Villarreal in 2007 and went on to score 82 goals in nearly 200 appearances for the club before his injury problems surfaced.
He joins Fiorentina on a four-year contract, although no timetable has been set for his return to action.
Fiorentina is fourth in Serie A at the midway point of the season.