The Osum is a river in southern Albania, one of the source rivers of the Seman. Its source is in the southwestern part of the Korçë County, near the village Vithkuq at an altitude of . It flows initially south to the Kolonjë municipality, then west to Çepan, and northwest through Çorovodë where it flows through the famous Osum Canyon, Poliçan, Berat and Urë Vajgurore. It joins the Devoll near Kuçovë, to form the Seman. The discharge of the river is reported to vary between /s and /s.