Loudon County is a county in the U.S. state of Tennessee. It is located in the central part of East Tennessee. As of the 2020 census, the population was 54,886. Its county seat is Loudon. Loudon County is included in the Knoxville, TN Metropolitan Statistical Area.

Loudon is a city in and the county seat of Loudon County, Tennessee, United States. Its population was 6,001 at the 2020 census. It is included in the Knoxville, Tennessee Metropolitan Statistical Area. The city is located in East Tennessee, southwest of Knoxville, on the Tennessee River. Fort Loudoun, the colonial era fort for which the city was named, is located several miles to the south in Monroe County.