Mr O’Brien had put a price tag of about €220m on the resort, according to the person who asked not to be named.
A spokesman for Mr O’Brien declined to comment.
One of Ireland’s richest men, Mr O’Brien has had mixed fortunes of late in selling assets.
In an unexpected move earlier this week the businessman announced that he had struck a deal with Canada’s Alimentation Couche-Tard to buy his Topaz chain of convenience stores and fuel retail businesses across the country.
Couche-Tard, which employs about 100,000 people across its network in north America, Europe, Asia and the Middle East, indicated that the entire Topaz workforce would be retained.
Denis O’Brien halts sale of exclusive Portugal resort Quinta do Lago https://t.co/OQD3K4Hfme— breakingnews.ie (@breakingnewsie) December 4, 2015
No price was disclosed by either party.
In October, he pulled a share sale by Digicel Group, halting what would have been the second-biggest initial public offering (IPO) in the US this year.
Mr O’Brien is worth $4.2bn, according to the Bloomberg Billionaires Index.
He bought Quinta do Lago in the late 1990s for an undisclosed price, becoming the third owner of the resort that’s more than four times the size of Monaco.
Set across 2,000 acres of land on the southern tip of Portugal, Quinta do Lago’s three golf courses, five-star hotels and multi-million-dollar villas facing the ocean have been a magnet for celebrities ranging from the late Formula One driver Ayrton Senna to Princess Caroline of Monaco.
The five-star Conrad Algarve, The Four Seasons and the Quinta do Lago are among the resort’s hotels.
A buyer would have controlled 25 acres of residential plots, 31 acres of commercial development opportunities and over 140 acres of residential development potential, according to a sales brochure.
“Quinta do Lago is without a doubt one of Europe’s most exclusive holiday destinations,” said Alison Buechner Hojbjerg, a director at Quinta Properties, a real estate agency selling luxury villas at the resort. “But the asking price was clearly a high price.”
Reports over the summer indicated Mr O’Brien had received a number of bids for the resort including from a US consortium.
Lone Star Funds bought the Vilamoura resort, also in the Algarve region, from struggling Spanish savings bank Catalunya Banc and Algarvetur in March for an undisclosed amount.