Chiuro is a comune (municipality) in the Province of Sondrio in the Italian region of Lombardy, located about 100 km northeast of Milan and about 9 km east of Sondrio, on the border with Switzerland. As of 31 December 2004, it had a population of 2,499 and an area of 51.8 km2. The municipality of Chiuro contains the frazioni (subdivisions, mainly villages and hamlets) Castionetto and Casacce. Chiuro borders the following municipalities: Brusio (Switzerland), Castello dell'Acqua, Lanzada, Montagna in Valtellina, Ponte in Valtellina, Poschiavo (Switzerland), Teglio.

Demographic evolution