Petersfield is a market town and civil parish in the East Hampshire district of Hampshire, England. It is 15 miles (24 km) north of Portsmouth. The town has its own railway station on the Portsmouth Direct line, the mainline rail link connecting Portsmouth and London. Situated below the northern slopes of the South Downs, Petersfield lies wholly within the South Downs National Park.

The South Downs National Park is England's newest national park, designated on 31 March 2010. The park, covering an area of 1,627 square kilometres (628 sq mi) in southern England, stretches for 140 kilometres (87 mi) from Winchester in the west to Eastbourne in the east through the counties of Hampshire, West Sussex and East Sussex. The national park covers the chalk hills of the South Downs and a substantial part of a separate physiographic region, the western Weald, with its heavily wooded sandstone and clay hills and vales. The South Downs Way spans the entire length of the park and is the only National Trail that lies wholly within a national park.