Sedilo is a comune (municipality) in the Province of Oristano in the Italian region of Sardinia, about 110 km north of Cagliari and about 40 km northeast of Oristano. It borders the municipalities of Aidomaggiore, Bidonì, Dualchi, Ghilarza, Noragugume, Olzai, Ottana and Sorradile. The Sanctuary of San Costantino Imperatore in Sedilo, whose main church was built in the 16th century around a 6th-century one. It is in Gothic-Catalan style.