Walnut Hill is a census-designated place (CDP) in Sullivan County, Tennessee.

[5] It is part of the Kingsport-Bristol-Bristol, TN-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.

[6] According to the United States Census Bureau, the CDP has a total area of 4.3 square miles (11 km2), all of it land.

As of the census[3] of 2000, there were 2,756 people, 1,134 households, and 877 families residing in the CDP.

20.0% of all households were made up of individuals, and 8.5% had someone living alone who was 65 years of age or older.