Moncestino () is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about east of Turin and about northwest of Alessandria. As of 31 December 2004, it had a population of 238 and an area of .
Moncestino borders the following municipalities: Crescentino, Fontanetto Po, Gabiano, Verrua Savoia, and Villamiroglio.