Castellarano (Reggiano: Castlarân) is a comune (municipality) in the Province of Reggio Emilia in the Italian region Emilia-Romagna, located about 45 kilometres (28 mi) west of Bologna and about 20 kilometres (12 mi) southeast of Reggio Emilia.
Castellarano borders the following municipalities: Baiso, Casalgrande, Prignano sulla Secchia, Sassuolo, Scandiano, Viano.