The Stewart River is a tributary of Yukon River in the Yukon Territory of Canada. It originates in the Selwyn Mountains, which stand on the border between the Northwest Territories and the Yukon Territory. From there, the Stewart flows west, past the village of Mayo. The river is crossed by the Klondike Highway at the village of Stewart Crossing, and the highway parallels the river westward for about . After leaving the highway, the river travels southwest until it intersects the Yukon River south of Dawson City. The mostly abandoned village of Stewart River is located at the mouth of the river.