The Buckhannon River is a 45.4-mile-long (73.1 km) tributary of the Tygart Valley River in north-central West Virginia, USA. Via the Tygart Valley, Monongahela and Ohio rivers, it is part of the watershed of the Mississippi River, draining an area of 309 square miles (800 km2) on the unglaciated portion of the Allegheny Plateau. It provides drinking water for much of Upshur County.