This gazelle inhabits flood plains and flat savanna grasslands in South Sudan, east of the Nile.

This monotypic species is often considered a subspecies of Thomson's gazelle (Eudorcas thomsonii) by many authors, such as Alan W. Gentry of the Natural History Museum, London.

[4] On the other hand, in their 2011 publication Ungulate Taxonomy, Grubb and Groves consider the gazelle as a full-fledged species in the genus Eudorcas.

[6] The vernacular name derives from Mongalla, a community in Central Equatoria state of South Sudan.

[6] The Mongalla gazelle inhabits flood plains and flat savanna grasslands in southeastern Sudan, east of the Nile.

[9] In 1999, Rod East of the IUCN SSC Antelope Specialist Group gave a population estimate of 100,000, but it was known that numbers change substantially in the area of its range and some parts are not even accessible.

A 2007 aerial survey in part of South Sudan gave a population estimate of 278,000.

[1] The animal follows a nomadic annual migration cycle over the eastern Sudd floodplains.

In the wet season, Mongalla gazelles congregate in high densities, along with other migratory species such as the white-eared kob and tiang.

[9] In fact, 1.2 million white-eared kob, tiang and Mongalla gazelles have continued their migration in South Sudan despite nearly 30 years of civil war in that area.

The population in the Boma ecosystem has been found to be stable and not under a great risk from hunting.