The Cedar Swamp River is a small river in Lakeville, Massachusetts that flows 4.6 miles (7.4 km) in a northwesterly direction through the western part of the town to where it forms the Assonet River near the Freetown line, just south of the village of Myricks. It is a tributary of the Taunton River.
The river is crossed by a railroad line that was originally built as the Taunton and New Bedford Railroad in 1840. It is now operated by CSX.
Coordinates: 41°49′12″N 71°01′44″W / 41.820°N 71.029°W