The Karns community is located in Northwest Knox County in the Beaver Creek Valley between Beaver Ridge and Copper Ridge. Karns was originally called Beaver Ridge. In 1913, the high school was completed and named after Professor T.C. Karns, the first Superintendent of Public Instruction for Knox County. In the 1950s, the community voted to be renamed "Karns."
Karns began as a farming community, but it has grown to also be home to subdivisions, small businesses, schools, and light industry.
Karns is the site of several public schools operated by Knox County Schools. Public elementary schools in the area are Karns Elementary School, Ball Camp Elementary School, and Hardin Valley Elementary School. One middle school, Karns Middle School, includes grades 6, 7, and 8. The community's long-time high school is Karns High School. A new high school, Hardin Valley Academy, opened in 2008 to reduce pressure on Karns, Farragut, and Bearden High Schools due to growth in the student population in western Knox County.