John Barnwell (July 15, 1748 – August 27, 1800) was a soldier and public official from South Carolina. He was the son of Nathaniel Barnwell and Mary Gibbes. During the American Revolution, he served in the South Carolina Provincial Congress (1775–1776) and the first South Carolina General Assembly (1776). 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.