The river is a continuation of the western branch of the Balonne River in southern Queensland, near Dirranbandi, and flows generally south-west across parts of the Darling Riverine Plains, joined by ten tributaries, including the Balonne and Birrie rivers, before forming its confluence with the Darling River near Bourke; descending 78 metres (256 ft) over the course of its 489 kilometres (304 mi) length.
Culgoa is an Aboriginal word meaning "running through" or "returning".
Cubbie Station, located on the Culgoa River, is situated adjacent to a large diversion channel which permits the farm, under licence to store 460,000 megalitres (16,000×10^6 cu ft) of river water. According to downstream farmers in 2008, large cotton farms, such as Cubbie Station, have reduced the traditional flow of the Culgoa River by one third. By 2009, downstream farmers where claiming that due to upstream water entitlements on the Culgoa River, since 2000, the Lower Balonne floodplain had not received enough water to flood the plains. Prior to the granting of these rights, the Lower Balonne River flooded every two or three years; impacting the sustainability of flora, fauna, birdlife, and economic returns from grazing livestock and cropping.
Little Culgoa Creek, an anabranch of the Culgoa River, leaves the river near Goodooga and returns to the river near Brenda Gate.