It is named after the former Kingdom of Gera, whose territory was approximately the same as the modern woreda.
Part of the Jimma Zone, Gera is bordered on the south by the Gojeb River which separates it from the Southern Nations, Nationalities and Peoples Region, on the northwest by Sigmo, on the north by Setema, on the northeast by Gomma, and on the east by Seka Chekorsa.
The administrative center of this woreda is Chira; other towns in Gera include Cheriko and Dusta.
The altitude of this woreda ranges from 1390 to 2980 meters above sea level; mountains include Waka, Kimbibit and Timba.
A survey of the land in this woreda shows that 26.5% is arable or cultivable (23.4% was under annual crops), 7.0% pasture, 56.6% forest, and the remaining 9.9% is considered degraded, built-up or otherwise unusable.