Casargo (Valassinese Lombard: Casarch) is a comune (municipality) in the Province of Lecco in the Italian region Lombardy, located about 70 kilometres (43 mi) north of Milan and about 20 kilometres (12 mi) north of Lecco.

Casargo borders the following municipalities: Crandola Valsassina, Margno, Pagnona, Premana, Primaluna, Taceno, Tremenico, Vendrogno.