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 4th most populous city. It is a principal city of the Gulfport–Biloxi metropolitan area, home to 416,259 residents in 2020. The area's first European settlers were French colonists.

Fort Maurepas, later known as Old Biloxi, was developed in colonial French Louisiana in April 1699 along the Gulf of Mexico . Fort Maurepas was designated temporarily as the capital of Louisiana in 1699. The capital was moved from Ocean Springs to Mobile in 1710, then to New Orleans in 1723 on the Mississippi River. Government buildings in the latter city were still under construction.