Williamson is a city in Mingo County, West Virginia, USA, along the Tug Fork River. The population was 3,414 at the 2000 census. It is the county seat of Mingo County^GR6, and is home to Southern West Virginia Community College.

Williamson is the site of a large rail yard built by the former Norfolk and Western Railroad (now Norfolk Southern Railway), which was built to service the many coal mines of the region. The city is protected by a floodwall, completed by the U.S. Army Corps of Engineers in 1984 in response to a devastating flood along the Tug Fork River in 1977. Floodgates were also built on the river's main entrance to Williamson, to completely close the city from floodwaters. The only use of the gates thus far occurred in 2002 during a major flood in the region.