Southwick is a town in the Adur district of West Sussex, England located five miles (8 km) west of Brighton. It covers an area of 863.7 ha. In 2001 it had a population of 13,195.

Adur is a local government district in West Sussex, England. It is named after the River Adur which flows through the area. The council is based in the town of Shoreham-by-Sea, and the district also contains the town of Southwick, the large village of Lancing and a modest rural hinterland inland. The district had a population of 64,626 at the 2021 census.