The Nile Lechwe is confined to seasonally flooded swamps and grasslands within the Sudd and Machar-Gambella wetlands of South Sudan and south-western Ethiopia. They are almost always on the edge of deeper swamps where the water is shallow (between 10 and 40 cm deep; Mefit-Babtie 1983).

The Nile Lechwe is found only in South Sudan and Ethiopia. The largest part of its range occurs in the Sudd swamps along the Bahr-el-Ghazal (White Nile) and Sobat rivers. There is a smaller population in the Machar marshes near the Ethiopian border, extending marginally into Gambella National Park (N.P.) in south-west Ethiopia, where its survival is highly precarious because of expanding human activities (Hillman and Fryxell 1988, East 1999, Falchetti and Kingdon 2013). An aerial survey of the Sudd in the 2007 dry season recorded Nile Lechwe widely along the White Nile and Sobat rivers (Fay et al. 2007).

In South Sudan, populations of Nile Lechwe occur in three nominal protected areas: Zeraf Game Resereve, extending over 9,700 km² along the Bahr-el-Zeraf; Fanyikang, over 480 km², north of Bahr-el-Gazal, which separates them from the Zeraf Reserve; and Shambe, over 620 km², along Bahr-el-Gebel. However, Nile Lechwe move in and out of these nominally protected areas and most occur in areas that are shared seasonally with huge herds of cattle. In Ethiopia, they occur marginally in Gambella N.P.

Falchetti (1998) outlined priorities for both in situ and ex situ conservation of this species. There is an increasing population of Nile Lechwe held in captivity (Falchetti 1998) though the captive population is based on a small number of founders.