Grantsville is a town in Calhoun County, West Virginia, in the United States. The population was 561 at the 2010 census. It is the county seat of Calhoun County. The town was established along the Little Kanawha River in 1865 and named for Ulysses S. Grant. Grantsville is home to Wayne Underwood Park, which includes a .25-mile-long walking trail, and to the annual West Virginia Wood Festival.