Carrosio is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 156 kilometres (97 mi) southeast of Turin and about 45 kilometres (28 mi) southeast of Alessandria. As of 31 December 2004, it had a population of 468 and an area of 7.2 square kilometres (2.8 sq mi).

Carrosio borders the following municipalities: Gavi and Voltaggio.

Demographic evolution