Sayo is one of the districts in the Oromia Region of Ethiopia. This district received its name from the name of the Oromo tribe (Sayyoo') that settled it first, Dembidolo which is a separate district now is part of the Kelem Welega Zone. Sayo is bordered on the south by the Gambela Region, on the west by , on the north by Yemalogi Welele, on the northwest by Hawa Gelan, and on the east by the Birbir River which separates it from the Illubabor Zone.