ACF Fiorentina, commonly referred to as Fiorentina ([fjorenˈtiːna]), is an Italian professional football club based in Florence, Tuscany, Italy. The original team was founded by a merger in August 1926, while the actual club was refounded in August 2002 following bankruptcy. Fiorentina have played at the top level of Italian football for the majority of their existence; only four clubs have played in more Serie A seasons.

Fiorentina has won two Italian league titles, in 1955–56 and again in 1968–69, as well as six Coppa Italia trophies and one Supercoppa Italiana. On the European stage, Fiorentina won the UEFA Cup Winners' Cup in 1960–61 and lost the final one year later. They finished runners-up in the 1956–57 European Cup, losing against Real Madrid, and also came close to winning the 1989–90 UEFA Cup, finishing as runners-up against Juventus after losing the first leg in Turin and drawing in the second one in Avellino.

Fiorentina is one of fifteen European teams that have played in the finals of all three major continental competitions: the Champions League (1956–1957, the first Italian team to reach the final in the top continental competition), the UEFA Cup Winners (1960–1961 and 1961–1962) and the UEFA Cup (1989–1990).

Since 1931, the club have played at the Stadio Artemio Franchi, which currently has a capacity of 43,147. The stadium has used several names over the years and has undergone several renovations. Fiorentina are known widely by the nickname Viola, a reference to their distinctive purple colours.