Fiorentino (Romagnol: Fiurentêin) is one of the nine castelli of San Marino.

It borders the San Marino municipalities Chiesanuova, San Marino, Borgo Maggiore, Faetano, and Montegiardino and the Italian municipalities Monte Grimano and Sassofeltrio.

[2][3] Fiorentino was added due to the last territorial expansion of San Marino, in 1463.

Evidence indicates a settlement existed on the site before Roman times.

Tre Fiori FC, one of the most successful clubs in Sammarinese football, is based in Fiorentino.