Hamer Bena was one of the 77 woredas in the Southern Nations, Nationalities and Peoples' Region of Ethiopia. Part of the Debub Omo Zone, Hamer Bena was bordered on the south by Kenya, on the southwest by Kuraz, on the northwest by the Usno River which separates it from Selamago, on the north by Bako Gazer, on the northeast by the Konso special woreda, and on the east by the Oromia Region; the Weito River separated it from Konso and the Oromia Region and the Neri River defined part of the boundary with Bako Gazer. Hamer Bena included part of Lake Chew Bahir along its southeastern border. The administrative center was Dimeka; other towns in Hamer Bena included Arbore, Key Afer, and Turmi. Hamer Bena was separated for Hamer and Bena Tsemay woredas.
This woreda is located in part of the semi-arid lowlands which support agro-pastoral groups who are at various stages of transition from nomadic to sedentary livelihoods. Part of the northwestern corner is included in the Mago National Park.