The Sebec River is a tributary of the Piscataquis River in Piscataquis County, Maine. From the outflow of Sebec Lake (45°16′13″N 69°06′54″W / 45.2704°N 69.1151°W) in Sebec, the river runs 10.0 miles (16.1 km) east and southeast to its confluence with the Piscataquis in Milo.