Piney Flats is an unincorporated community in Sullivan County in the U.S. state of Tennessee. It is part of the Kingsport–Bristol (TN)–Bristol (VA) Metropolitan Statistical Area, which is a component of the Johnson City–Kingsport–Bristol, TN-VA Combined Statistical Area – commonly known as the "Tri-Cities" region. Some areas of Piney Flats along U.S.