Osio Sotto (Bergamasque: ) is a comune (municipality) in the Province of Bergamo in the Italian region of Lombardy, located about northeast of Milan and about southwest of Bergamo. As of 31 December 2004, it had a population of 11,097 and an area of .
Founded in Roman times, the comune is currently the tenth municipality in the province of Bergamo by population, and the fourth of the southern Bergamo region.
Osio Sotto borders the following municipalities: Boltiere, Brembate, Filago, Levate, Osio Sopra, Verdellino.