Hamblen County is a county located in the U.S. state of Tennessee. As of the 2020 census, the population was 64,499. Its county seat and only incorporated city is Morristown. Hamblen County is the core county of the Morristown, Tennessee Metropolitan Statistical Area, which includes Hamblen and Jefferson counties. The county and the Morristown MSA are included in the Knoxville-Morristown-Sevierville, TN Combined Statistical Area.