Wilmington Island is an unincorporated community and census-designated place in Chatham County, Georgia. The population was 15,129 at the time of the 2020 U.S. census. It is part of the Savannah metropolitan area. The communities of Wilmington Island form a large and affluent suburb of Savannah, where most residents work. The island lies east of Savannah between the town of Thunderbolt and the beach city of Tybee Island.