The McArthur River is a 521 km long river in the Northern Territory of Australia which flows into the Gulf of Carpentaria at Port McArthur, opposite the Sir Edward Pellew Group of Islands. The river was named by Ludwig Leichhardt while he explored the area in 1845. He named the River after James MacArthur and the MacArthur family of Camden, who were enthusiastic supporters of his expedition. The McArthur River has significance for the local Aboriginal communities, who use it for fishing and other traditional activities.
The McArthur River basin covers 20,010 km2. The basin is situated between the Rosie River catchment to the north, the Limmen Bight River to the east, the Barkly River catchment to the south and the Robinson River catchment to the west. The mean annual runoff is 3,270,000 ML per year. The headwaters of the rivers rise on the northern edge of the Barkly Tableland. Tributaries of the McArthur River include Tooganginie Creek, and the Kilgour and Clyde rivers.
The river has a long tidal estuary which extends inland to the town of Borroloola. The estuary is in near-pristine condition, and forms part of the Port McArthur Tidal Wetlands System Important Bird Area.
