Okaloosa County is located in the northwestern portion of the U.S. state of Florida, extending from the Gulf of Mexico to the Alabama state line. As of the 2020 census, the population was 211,668. Its county seat is Crestview. Okaloosa County is included in the Crestview-Fort Walton Beach-Destin, FL Metropolitan Statistical Area.

Crestview is the largest city in Okaloosa County, Florida, United States. The population was 27,134 at the 2020 census, up from 20,978 at the 2010 census. It is the county seat of Okaloosa County. With an elevation of 235 feet (72 m) above sea level, it is one of the highest points in the state.