Saint-Louis is a commune located on the southwest coast of Réunion, a French overseas department in the Indian Ocean. It is the fifth-largest commune on the island and lies adjacent to the larger city of Saint-Pierre.
The commune forms part of Réunion's southwestern region, an area characterized by the island's volcanic landscape and coastal geography. As a significant population center, Saint-Louis contributes to the demographic and economic composition of this section of Réunion.