The demolition of the Thorpe Park Estate in the 1930s transformed the grounds into a gravel pit, originally owned by Ready Mixed Concrete Limited. RMC excavated gravel from the site for 30 years from 1941 until 1970 when they began to plan a transformation of the site into a leisure based visitor attraction. Initial concepts planned for the attraction to be themed around the 'History of the British People as a Maritime Nation' achieved by flooding the now empty gravel pits

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 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, his final public appearance shortly before he was assassinated by a bomb on board a fishing boat planted by the Provisional IRA in Mullaghmore, Ireland. In addition to lakes and parkland, the park featured a replica Stone Age cave, Celtic farm, Norman castle and Viking camp as well as ancient water vehicles and aircraft.

In the early 1980s, the park was redeveloped into a theme park with permanent themed rides and attractions. New attractions were opened throughout the 1980s and 1990s. Space Station Zero was the park's first rollercoaster, opening in 1984. The last large attraction opened by the park's original owners was "X:\No Way Out" in 1996. Both attractions still operate to this day but under the names 'Flying Fish' and 'The Walking Dead: The Ride' respectively.

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

In 1998, The Tussauds Group bought the park. This period saw large 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, Blackstone Group purchased The Tussauds Group for $1.9 billion (USD) and the company was merged into Merlin Entertainments, who took over operation of Thorpe Park. Dubai International Capital also acquired 20% of Merlin Entertainments.

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

The target audience for the resort is teenagers and young adults, with rides such as 'Saw – The Ride' in 2009 and 'The Swarm' in 2011 being added. In 2014, Merlin also decided to target a broader family-based market with new attractions such as Angry Birds Land and the park's onsite hotel.

On 20 February 2019, the official Twitter account of Thorpe Park confirmed the permanent closure of Logger's Leap, a log flume that had opened in 1989 but had been closed since 2015 due to the Smiler accident at Alton Towers that year.

In 2021, Thorpe Park announced plans for a new rollercoaster in the Old Town section of the park under the project name of Project Exodus. During the 2023 Fright Nights event the name was revealed to be 'Hyperia' and it was set to be the tallest and fastest rollercoaster in the UK, at a height of 236 feet (71.9 metres) and a speed of 81 mph (130 km per hour).

In preparation for the opening of Hyperia, Merlin announced major new investment for the older areas of the park to get them up to standard ready for the record breaking new rollercoaster. This began on the 30 October 2023 when Thorpe Park announced that Angry Birds Land would be permanently closing. The park closed for the 2023 season on Tuesday 31 October following the conclusion of that years Fright Nights event. Over the closed season the Sparkle Project began which was a large refurbishment of many areas of the park which saw the refitting of many shops, repaint work for Colossus and Stealth, a new footbridge over Tidal Wave and much more. On 16 November 2023, the park revealed that the Angry Birds Land would be rethemed to Big Easy Boulevard and on the 30 November 2023 Thorpe Park revitalised their branding, with a brand new logo (previously unchanged since 2008) and slogan, bidding farewell to their iconic "infinity" symbol (used for the park since 2001) and light-hearted An Island Like No Other tagline - instead marketing itself as the home of Feel-Good Thrills. The new logo comes with six palettes and patterns for their marketing materials and merchandise, stating that this “encapsulates the spirit of Thorpe Park”.

The park re-opened for the 2024 season on 24 March with Big Easy Boulevard opening and construction on Hyperia completed. On 27 March 2024, Thorpe Park announced Hyperia's opening date of the 24 May 2024. The rollercoaster began testing on 16 April and cycled nearly everyday up until its press event on the 23 May when the first public riders were allowed on.

Hyperia, the UK's tallest and fastest rollercoaster opened to the public at the park on the planned date. However, on the morning of 25 May 2024, the park announced on social media that Hyperia would be closed until the 29 May due to 'unforeseen circumstances.' The re-opening was then delayed until 8 June via another social media post. The final delay to the re-opening date pushed it back to the 12 June where it did re-open successfully. The coaster would go on to valley two times once on 19 June and the 2 October 2024 but then operate reliably for the rest of the 2024 season. Then in 2025 the ride had major downtime due to an issue with one of the drive tyres before the lift hill, and would then proceed to valley on the 2nd of April. This would be in different circumstances to the others, as it would proceed to valley when a delay was occurring and it was a test car, as opposed to the other circumstances where it valleyed in morning tests.