Cusio (Bergamasque: ) is a comune (municipality) in the Province of Bergamo, in the Italian region of Lombardy. It is located about northeast of Milan, and about north of Bergamo. As of 31 December 2004, it had a population of 286 and an area of .
Cusio borders the following municipalities: Cassiglio, Gerola Alta, Ornica, Santa Brigida.