John Barnwell (July 15, 1748 – August 27, 1800) was a soldier and public official from South Carolina.
As a major in the South Carolina militia during the American Revolutionary War, he was captured at Charlestown in 1780 and was later released in a prisoner exchange.
He was appointed a general in the South Carolina militia after the war.
He frequently served in the South Carolina Senate from 1778 until his death.
In 1795, he was elected to the 4th United States Congress but declined to serve.