Lake Muhazi is located in the eastern part of Rwanda. It is accessible from three of Rwanda's primary routes. The Kigali to Gatuna road passes close to the lake's western end, the Kigali to Kayonza road, which runs parallel to the lake to the south; finally, the Kayonza to Kagitumba road runs along the lakeshore for 3.8 kilometres (2.4 mi) near Gahini, before passing over two of the ridges emanating from the lake and finally leaving the lake near Kawangire.
Lake Muhazi is 60 km long, in an east-west direction, but its width is less than 5 km. It is located in east-central Rwanda and has shoreline in three of the country's five provinces. The western third of the lake forms the border between Kigali Province (Gasabo District) to the south, and Northern Province (Gicumbi District) to the north. The eastern two-thirds or the lake is in the Eastern Province, forming the border between Rwamagana District to the south, and Gatsibo and Kayonza Districts to the north