Whitemarsh Island is an unincorporated community and census-designated place (CDP) in Chatham County, Georgia, United States. The population was 6,983 at the 2020 U.S census. It is part of the Savannah metropolitan statistical area. The communities of Whitemarsh Island are a relatively affluent suburb of Savannah.

Chatham County is located in the U.S. state of Georgia, on the state's Atlantic coast. The county seat and largest city is Savannah. One of the original counties of Georgia, Chatham County was created February 5, 1777, and is named after William Pitt, 1st Earl of Chatham.