St. Simons Island is a barrier island and census-designated place (CDP) located on St. Simons Island in Glynn County, Georgia, United States. The names of the community and the island are interchangeable, known simply as "St. Simons Island" or "SSI", or locally as "The Island". St. Simons is part of the Brunswick metropolitan statistical area, and according to the 2020 U.S. census, the CDP had a population of 14,982. Located on the southeast Georgia coast, midway between Savannah and Jacksonville, St. Simons Island is both a seaside resort and residential community. It is the largest of Georgia's renowned Golden Isles. Visitors are drawn to the Island for its warm climate, beaches, variety of outdoor activities, shops and restaurants, historical sites, and natural environment.

Glynn County is located in the southeastern part of the U.S. state of Georgia. As of the 2020 census, the population was 84,499. The county seat is Brunswick. Glynn County is part of the Brunswick, Georgia Metropolitan Statistical Area.