Littlehampton is a seaside resort town and civil parish in the Arun District of West Sussex, England, on the east bank at the mouth of the River Arun. It lies 51.5 miles (83 km) south southwest of London, 17.5 miles (28 km) west of Brighton and 11 miles (18 km) east of the county town of Chichester.

The parish covers an area of 11.35 km² (4 sq mi) and has a population of 25,593 (2001 census).The Sub-Urban Area of the town has a population of approx 55,000. The conurbation includes other settlements: Wick in the north west; Lyminster to the north; East Preston, Rustington and Angmering to the east. Wick and Toddington became part of the town in 1901. Nearby towns include Bognor Regis west southwest and Worthing to the east. The town is also the westernmost settlement of the 12th largest urban area in the UK, the Brighton/Worthing/Littlehampton conurbation, a region encompassing some 461,181 people (2001 census).