Lafayette is the most populous city in and parish seat of Lafayette Parish in the U.S. state of Louisiana, located along the Vermilion River. It is Louisiana's fourth-most populous city with a 2020 census population of 121,374; the consolidated city-parish's population was 241,753 in 2020. The Lafayette metropolitan area was Louisiana's third largest metropolitan statistical area with a population of 478,384 at the 2020 census. The Acadiana region containing Lafayette is the largest population and economic corridor between Houston, Texas and New Orleans.

Lafayette, Vermilionville, or the Lafayette metropolitan statistical area per the U.S. Office of Management and Budget, is the third largest metropolitan statistical area in the U.S. state of Louisiana. Located in the south central Acadiana region, it covers five parishes. At the 2020 U.S. census, 478,384 people lived in the metropolitan area, making it the 116th most populous in the United States and one of Louisiana's fastest growing metropolises; in 2010, its population was 273,738 and it outpaced the Shreveport–Bossier City metropolitan area in 2015.