Gueydan is a town in Vermilion Parish, Louisiana, United States. The population was 1,398 at the 2010 census, down from 1,598 in 2000. At the 2020 population estimates program, its population decreased to 1,328. It is part of the Abbeville micropolitan statistical area.

Vermilion Parish is a parish located in the U.S. state of Louisiana, created in 1844. The parish seat is Abbeville. Vermilion Parish is part of the Lafayette metropolitan statistical area, and located in southern Acadiana. At the 2020 U.S. census, the population was 57,359.