According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.9%) is water. The southern part of Sevier County is located within the Great Smoky Mountains, and is protected by the Great Smoky Mountains National Park. The northern parts of the county are located within the Ridge-and-Valley Appalachians. Sevier contains the highest point in Tennessee, Clingmans Dome, which rises to along the county's border with North Carolina. Mount Guyot, located in the Eastern Smokies in the extreme eastern part of the county, is the state's second-highest mountain at . The Mount Le Conte, a very prominent mountain visible from much of the central part of the county, is the state's third-highest.