Sennariolo is a comune (municipality) located about northwest of Cagliari and about north of Oristano in the Province of Oristano, Sardinia, Italy. As of 31 December 2004, it had a population of 185 and an area of .
Sennariolo borders the following municipalities: Cuglieri, Flussio, Scano di Montiferro, Tresnuraghes.