Castellino Tanaro () is a comune (municipality) in the Province of Cuneo in the Italian region Piedmont, located about southeast of Turin and about east of Cuneo.
Castellino Tanaro borders the following municipalities: Ceva, Igliano, Lesegno, Marsaglia, Niella Tanaro, Roascio, and Rocca Cigliè.
Castellino Tanaro is twinned with: