San Giorgio Monferrato (in Piedmontese San Giòrs Monfrà) is a comune of the Province of Alessandria in the Italian region Piedmont. It is about east of the regional capital Turin and about northwest of Alessandria.
The territory of this small rural commune of the Monferrato Casalese extends over an area of . Its population of 1,293 is concentrated in the village of San Giorgio (Saint George). The communal coat of arms pictures the saint killing the dragon. San Giorgio clusters around a medieval castle on a low hill southwest of Casale Monferrato, which dominates the road from Casale to Asti.
San Giorgio Monferrato borders the following municipalities: Casale Monferrato, Ozzano Monferrato, and Rosignano Monferrato.
San Giorgio Monferrato is twinned with: