Sesimbra is a municipality located in the Setúbal District of Portugal. It is situated at the foothills of the Serra da Arrábida mountain range, which lies between the cities of Setúbal and Sesimbra.
The town is characterized by its position at the Setúbal Bay near the mouth of the Sado River. Because of its natural harbor, it serves as an important fishing town. As of 2011, the municipality had a population of 49,500 and covers an area of 195.47 km².