San Pietro in Cerro is a comune (municipality) in the Province of Piacenza in the Italian region Emilia-Romagna, located about 120 kilometres northwest of Bologna and about 20 kilometres east of Piacenza. As of 31 December 2004, it had a population of 962 and an area of 27.5 square kilometres. San Pietro in Cerro borders the following municipalities: Caorso, Cortemaggiore, Monticelli d'Ongina, Villanova sull'Arda.