Knoxville is a city in and the county seat of Knox County, Tennessee, United States, on the Tennessee River. As of the 2020 United State…Knoxville is a city in and the county seat of Knox County, Tennessee, United States, on the Tennessee River. As of the 2020 United States census, Knoxville's population was 190,740, making it the largest city in the East Tennessee Grand Division and the state's third-most-populous city after Nashville and Memphis. It is the principal city of the Knoxville metropolitan area, which had a population of 879,773 in 2020.