Duplin County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 48,715. Its county seat is Kenansville. The county was formed in 1750 from New Hanover County. It was named for Thomas Hay, Viscount Dupplin, as he was known when he served on the Board of Trade and Plantations in England in the 1740s.