Osio Sotto is a comune in the Province of Bergamo in the Italian region of Lombardy, located about 40 kilometres northeast of Milan and about 11 kilometres southwest of Bergamo. As of 31 December 2004, it had a population of 11,097 and an area of 7.5 square kilometres. 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.