Jonesborough is a town in, and the county seat of, Washington County, Tennessee, in the Southeastern United States. Its population was 5,860 as of 2020. It is "Tennessee's oldest town".

Located in the far northeast corner of the state, Jonesborough was founded by European Americans in 1779, 17 years before Tennessee became a state and while the area was under the jurisdiction of North Carolina. It was named after North Carolina legislator Willie Jones, who had supported the state's westward expansion across the Appalachian Mountains.