The demolition of the Thorpe Park Estate in the 1930s resulted in the grounds being converted into a gravel pit, originally owned by Ready Mixed Concrete Limited. RMC extracted gravel from the site for thirty years, from 1941 until 1970, at which point the company began planning to flood the expended gravel pits and develop the site into a leisure-based visitor attraction. In 1975, the Water Ski World Championships were held on the lake.

RMC established a subsidiary, Leisure Sport Limited, to operate the 400-acre (160 ha) park for water sports, leisure activities, and heritage exhibitions, at a cost of £3 million. The park was formally opened to the public by Lord Louis Mountbatten on 24 May 1979, in what would be his final public appearance before he was assassinated later that year by a bomb planted by the Provisional IRA on a fishing boat in Mullaghmore, Ireland. In addition to its lakes and parkland, the site featured a replica Stone Age cave, a Celtic farm, a Norman castle, and a Viking camp, as well as exhibits of historic watercraft and aircraft.

In the early 1980s, the park was redeveloped into a theme park with permanent themed rides and attractions. New large attractions were introduced throughout the 1980s, including Magic Mill, Phantom Fantasia, Thunder River, Logger's Leap and the Canada Creek Railway, along with the development of a central area of themed streets, shops and eateries. Space Station Zero was the park's first roller coaster, an indoor powered coaster, opened in 1984. New themed areas opened in the 1990s with Fantasy Reef and Ranger County. The last major attraction developed under Leisure Sport Ltd was the themed indoor roller coaster, X:\ No Way Out, in 1996 (now The Walking Dead: The Ride).

Between 1983 and 1989, the park was also used as a filming location for The Benny Hill Show.

In 1998, The Tussauds Group purchased the park. This period saw considerable investment, with major attractions opening such as Tidal Wave in 2000, Vortex in 2001, Colossus in 2002, Nemesis Inferno in 2003, and Stealth in 2006.

In May 2007, the Blackstone Group purchased The Tussauds Group for US$1.9 billion, and the company was merged into Merlin Entertainments, who took over operation of Thorpe Park. Dubai International Capital also acquired a 20% stake in Merlin Entertainments.

On 17 July 2007, as part of the financing for the Tussauds acquisition, Merlin sold Thorpe Park to the private investment firm Prestbury under a sale-and-leaseback agreement. The site is operated by Merlin under a renewable 35-year lease. As of 2023, the site is owned by LXi REIT plc.

The resort's target audience is primarily teenagers and young adults, with rides such as Saw – The Ride (2009) and The Swarm (2011) being introduced. In 2014, Merlin also sought to broaden the park's appeal to families with additions including Angry Birds Land and the park's onsite hotel.

On 20 February 2019, Thorpe Park's official Twitter account confirmed the permanent closure of Logger's Leap. In 2021, Thorpe Park announced plans for a new rollercoaster on the log flume's former site. During the 2023 Fright Nights event, the ride was officially revealed as Hyperia, planned to become the tallest and fastest roller coaster in the United Kingdom, reaching 236 feet (71.9 metres) in height and speeds of up to 81 mph (130 km/h). Hyperia opened on the 23 May 2024, when the first public riders were allowed on.

Also for 2024, Thorpe Park adopted a new logo and branding, which the park stated was to "encapsulate the spirit of Thorpe Park".