San Leonardo is a comune (municipality) in the Regional decentralization entity of Udine, in the Italian region of Friuli-Venezia Giulia. It lies in the far northeast of Italy, near the border with Slovenia.
The municipality is located about 60 kilometres (37 mi) northwest of Trieste and about 25 kilometres (16 mi) east of Udine. It borders the municipalities of Grimacco, San Pietro al Natisone, Savogna, Stregna, and Prepotto.