Mr McManus is believed to have paid in the region of €30m for the 5-star manor, which stands on more than 700 acres.
It was described by CBRE, the selling agents, as one of Ireland’s most luxurious manors and golf resorts.
Mr McManus already owns a major share in the world famous Sandy Lane hotel and resort in Barbados.
He has a palatial home adjacent to Sandy Lane.
Anita Higgins, general manager of Adare Manor, said yesterday : “I am very happy to confirm that JP, Noreen and the McManus family are now the owners of Adare Manor. We look forward to working with our new owners who have previously hosted two JP McManus ProAms here in the past.”
Mr McManus acquired full ownership of the manor and resort by winning the bidding battle after previous owner US businessman Tom Kane and his wife Judy put it up for sale.
The hotel has 62 suites and the golf course was designed by Robert Trent Jones Snr. The Rive Maigue flows through the grounds offering great salmon and trout fishing to visitors.
It is understood Mr McManus is one of seven parties who lodged bids for the resort in recent weeks.
US investor Tony Saliba, who recently bought Lough Erne golf resort in Co Fermanagh, was also linked to the property.
The hotel was bought in the mid-1980s by Tom Kan,e who made significant investments in the property over the years.
This included the development of the 18-hole championship golf course.
The course hosted the Irish Open in 2007 and 2008, as well as the JP McManus Pro Am, which attracted some of the world’s leading golfers, including Rory McIlroy and Tiger Woods, and a celebrities, including former US president Bill Clinton, and actors Hugh Grant and Samuel L Jackson.