Frassinello Monferrato is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about east of Turin and about northwest of Alessandria.
Frassinello Monferrato borders the following municipalities: Camagna Monferrato, Cella Monte, Olivola, Ottiglio, Rosignano Monferrato, and Vignale Monferrato.