Cassiglio (Bergamasque: ) is a comune (municipality) in the Province of Bergamo in the northern Italian region of Lombardy, located about northeast of Milan and about north of Bergamo.
Cassiglio borders the following municipalities: Camerata Cornello, Cusio, Olmo al Brembo, Ornica, Piazza Brembana, Santa Brigida, Taleggio, Valtorta, Vedeseta.