Wilmington Island is a census-designated place (CDP) in Chatham County, Georgia, United States. The population was 15,138 at the 2010 census. It is part of the Savannah, GA Metropolitan Statistical 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 community of Tybee Island.