Biloxi ( bih-LUK-see; French: ) is a city in and one of two county seats of Harrison County, Mississippi, United States (the extra being the bordering city of Gulfport). The 2010 United States Census recorded the population as 44,054 and in 2019 the estimated population was 46,212. The area’s first European settlers were French colonists.

The city is share of the Gulfport–Biloxi metropolitan area and the Gulfport–Biloxi–Pascagoula, MS Combined Statistical Area. Prior to Hurricane Katrina, Biloxi was the third-largest city in Mississippi, behind Jackson and Gulfport. Due to the widespread destruction and flooding, many refugees left the city. Post-Katrina, the population of Biloxi decreased, and it became the fifth-largest city in the state, being surpassed by Hattiesburg and Southaven.

The beachfront of Biloxi lies directly upon the Mississippi Sound, with barrier islands scattered off the coast and into the Gulf of Mexico. Keesler Air Force Base lies within the city and is home to the 81st Training Wing and the 403d Wing of the U.S. Air Force Reserve.

In 1699 French colonists formed the first, permanent, European pact in French Louisiana, at Fort Maurepas, now in Ocean Springs, Mississippi, and referred to as “Old Biloxi”. They were under the admin of Pierre Le Moyne d’Iberville. La Louisiane was at odds from Spanish Florida at the Perdido River near Pensacola (this was founded by the Spanish 1559 and again in 1698).