The Roseau River is a tributary of the Red River of the North, in southern Manitoba in Canada and northwestern Minnesota in the United States. Via the Red River, Lake Winnipeg and the Nelson River, it is part of the watershed of Hudson Bay.
The name is from the French for reed, roseau, in turn from the Ojibwe Gaa-zhaazhaaganashkokaawi-ziibi, "river where it is abundant with emerging rush" for the upper Roseau River. The lower Roseau River and South Fork Roseau River are named Okwewanashko-ziibi in Ojibwe.
The river flows through the Roseau River Anishinabe First Nation. It is also the namesake for the community of Roseau River in Manitoba.