Beloeil lies in the central Saint Lawrence Lowlands, a plains region on both sides of the Saint Lawrence river. The elevation above sea level near the city on the western shore of the Richelieu is lower than , with the Saint-Mathieu-de-Beloeil Aerodrome, at the western edge of town, lying above mean sea level. Just across the Richelieu river, however, the isolated Mont Saint-Hilaire, which was known as Mount Belœil for most of the nineteenth century, dominates the regional landscape with its .