The river originates in the Kelabit Highlands, a watershed demarcated by the Iran Mountains of East Kalimantan, which form a natural border with Sarawak.

The river flows westwards through tropical rainforest to the South China Sea.

[6] The Baram river basin, an area of some 10,000 square miles (30,000 km2), has been part of Sarawak since it was ceded to the White Rajah of Sarawak by the then sultan of Brunei in 1882, for a perpetual annual payment of 6,000 dollars.

[7] The river is crossed not far from its mouth by the Miri-Baram Highway, Federal Route 22, on the Batang Baram Bridge opened in 2003.

[9] "Long" meaning "confluence" is used by the Orang Ulu (upriver people).