Formed by the confluence of the Little Coleman River and Big Coleman River, the headwaters of the river rise under Lapunya Mount near The Lagoons in the Great Dividing Range and initially flows south. It flows past the Curlew Range and then turns west across the Boomerang Plain eventually discharging into the Gulf of Carpentaria between the mouth of the Mitchell River to the south and the settlement of Pormpuraaw to the north. From source to mouth, the Coleman River is joined by six tributaries including the King River and the Lukin River, and descends over its course.