It begins at the confluence of the Mbomou (mean annual discharge 1,350 m3/s) and Uele Rivers (mean annual discharge 1,550 m3/s) and flows west, forming the border between Central African Republic (CAR) and the Democratic Republic of the Congo (DRC).

Subsequently, the Ubangi bends to the southwest and passes through Bangui, the capital of the CAR, after which it flows south – forming the border between the DRC and the Republic of the Congo.

[3] It is believed that the Ubangi's upper reaches originally flowed into the Chari River and Lake Chad before being captured by the Congo in the early Pleistocene.

According to the plan, named Transaqua, the water from the Ubangi would revitalize Lake Chad and provide a livelihood in fishing and enhanced agriculture to tens of millions of central Africans and Sahelians.

Inter-basin water transfer schemes were proposed in the 1980s and 1990s by Nigerian engineer J. Umolu and the Italian firm Bonifica.