Grantsville is a town in Calhoun County, West Virginia, in the United States. The population was 565 at the 2000 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.
Grantsville is located at 38°55′23″N 81°5′42″W / 38.92306°N 81.095°W / 38.92306; -81.095 (38.922921, -81.094920).
According to the United States Census Bureau, the town has a total area of 0.5 square miles (1.2 km²), all land.