Onifai (Sardinian: Oniai) is a comune (municipality) in the Province of Nuoro in the Italian region of Sardinia, located about 200 kilometres (120 mi) north of Cagliari, about 40 kilometres (25 mi) east of Nuoro and just 5 kilometres (3 mi) inland from the gulf of Orosei. The economy is based on agriculture and shepherding. Onifai is well known for its pecorino cheese (most production is exported to the European continent, United States and Canada) and vernaccia wine made with Cannonau grapes. As of 31 December 2004, it had a population of 765 and an area of 43.0 square kilometres (16.6 sq mi).

Onifai borders the following municipalities: Galtellì, Irgoli, Orosei, Siniscola.