Caiolo is a [[comune]] (municipality) in the Province of Sondrio in the Italian region of Lombardy, located about 90 km northeast of Milan and about 5 km southwest of Sondrio. As of 31 December 2004, it had a population of 994 and an area of 33.3 km2.

Caiolo borders the following municipalities: Albosaggia, Carona,