Fort Walton Beach, often referred to by the initialism FWB, is a city in southern Okaloosa County, Florida, United States. As of the 2020 U.…Fort Walton Beach, often referred to by the initialism FWB, is a city in southern Okaloosa County, Florida, United States. As of the 2020 U.S. census, the population was 20,922, up from 19,507 in 2010. It is a principal city of the Crestview−Fort Walton Beach−Destin, Florida Metropolitan Statistical Area.