Johns Island, also spelled John's Island, is an island in Charleston County, South Carolina, United States, and is the largest island in the state of South Carolina. Johns Island is bordered by the Wadmalaw, Seabrook, Kiawah, Edisto, Folly, and James islands; the Stono and Kiawah rivers separate Johns Island from its border islands. It is the fourth-largest island on the US east coast, surpassed only by Long Island, Mount Desert Island and Martha's Vineyard. Johns Island is 84 square miles (220 km2) in area, with a population of 21,500 people.
Johns Island was named after Saint John Parish in Barbados by the first English colonial settlers on the island, who had come from there.
The island is home to scores of wildlife species, including deer, alligators, raccoons, coyotes, bobcats, otters and wild hogs. The rivers and marshes abound with fish and shellfish, especially oysters, and dolphins. The number of bird species is in the hundreds. They include bald eagles, osprey, wild turkeys, owls, hawks, herons, egrets and ducks. The flora is abundant, with many native and imported species as well as agricultural crops.
Johns Island was originally inhabited by nomadic tribes of Native Americans such as the Kiawah, who survived by hunting and collecting shellfish.