Located in the Arsi Zone of the Oromia Region 126 km (78 mi) south from Addis Ababa, this town has a latitude and longitude of 7°57′N 39°7′E / 7.950°N 39.117°E / 7.950; 39.117, with an elevation of 2,430 meters.

The 6th brigade and two companies of the 5th brigade of the King's African Rifles captured Asella on 10 April 1941, after pursuing General De Simone south from Dire Dawa and forcing their way past the Awash River and a dug-in Italian position.

In 1957, Asella was the southern end of the national telephone network, and by 1960, Asella had one of the ten municipal slaughter houses in Ethiopia; further, that year, a branch of the Ethiopian Electric Light and Power Authority had begun operation in the town.

[3] Asella has been the home of many long-distance runners, including Haile Gebrselassie, Kenenisa Bekele, Tirunesh Dibaba, and Derartu Tulu.

[1] The official estimate of population for mid 2022 produced a total of 139,537 inhabitants, of whom 69,459 were male and 70,078 were female.