Merlin Entertainments has agreed to be taken over by Kirkbi Invests, a company owned the founding family of Lego.
Private investor Blackstone will also provide capital for the transaction.
The deal values the company and its debt at nearly £6 billion, and when complete will see Merlin half owned by the Kirk Kristiansen family and half by Blackstone and Canadian pension fund, CPPIB.
Merlin owns the Madame Tussauds brand, Legoland theme parks, the London Eye, Alton Towers and Chessington Adventures, among other assets.
The move will be one of the biggest private equity deals in Europe in recent years, and comes as buyout firms are flush with record amounts of cash to invest.
“Following an unsolicited approach by a consortium of investors, and after rejecting a number of their proposals, the Merlin independent directors believe this offer represents an opportunity for Merlin shareholders to realise value for their investment in cash at an attractive valuation,” Merlin chairman John Sunderland said in a statement.
“We are therefore unanimously recommending it to our shareholders.”
The deal is expected to complete in the fourth quarter of 2019.
Kirkbi already owns almost a third of the shares in Merlin Entertainments, and says it does not expect the deal to lead to any significant changes.
All existing Merlin attractions in the UK will remain open and it has no plans to sell any part of the business, it said.
Merlin is the second-largest operator of visitor attractions globally with more than 130 attractions in 25 countries.
Earlier this year it sold its ski interests to Vail Resorts.