The Burnside River is a river in the Canadian territory of Nunavut. It has its headwaters at Contwoyto Lake, flows across the Precambrian Shield's Contwoyto Plateau, flows through isolated and rugged tundra, into Lake Kathawachaga, and through the Wilberforce Hills region. Before emptying into Bathurst Inlet on the Arctic Ocean, the Mara River empties into the Burnside River. The river has an island, Nadlak, historically notable for Inuit use of caribou antlers as hut roof infrastructures.
The river is surrounded by continuous permafrost. It is migratory crossing path of Bathurst barren-ground caribou. Wildlife includes Arctic wolf, grizzly bears and muskox, while birds include golden eagle, rough-legged hawk and gyrfalcon. Arctic char, Arctic grayling, lake trout, and whitefish are also found in the river. Plants along the shoreline include dwarf willow and alder, plus 125 different wild flowers.