Bay Saint Louis is a city located in Hancock County, Mississippi. It is part of the Gulfport-Biloxi, Mississippi Metropolitan Statistical Area. As of the 2000 census, the city had a total population of 8,209. It is the county seat of Hancock County. Like several other upper Gulf Coast cities, Bay Saint Louis was devastated by Hurricane Katrina in August 2005. Bay St. Louis apartments for rent comparison page shows most up to date rent information on Bay St. Louis apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.