Biloxi is a city in Harrison County, Mississippi, United States. It lies on the Gulf Coast in southern Mississippi, bordering the city of Gulfport to its west. The adjacent cities are both designated as seats of Harrison County. The population of Biloxi was 49,449 at the 2020 census, making it the state's fourth-most populous city. It is a principal city of the Gulfport–Biloxi metropolitan area, h…