Francis Bacon's Figure Writing Reflected in Mirror has sold for $44.9m at Sotheby's Contemporary Art Evening Sale in New York, up 12.2% on its $40m high estimate.
The striking work, produced in 1976, features a depiction of Bacon and his lover George Dyer as a single figure.
First exhibited at Bacon's Paris exhibition in 1977, it was bought by the consignor directly from the exhibition, and had remained away from public view in the same private collection for more than 30 years.
Described as a "very, very serious painting" by Sotheby's worldwide head of contemporary art, Tobias Meyer, in the UK's Guardian newspaper, the piece is the most important work by Bacon to appear on the market since the sale of Triptych 1976 in 2008.
In that year Triptych 1976 broke the world record for a post-war painting, selling for $86.3m to the Russian billionaire Roman Abramovich.
That record was broken earlier this week, when Mark Rothko's 1961 work Orange, Red, Yellow sold for $86.9m at Christie's.
Contemporary art is a huge boom area; the sector saw growth of 35% in 2011.
Art critic Scott Reyburn believes art investors opted for safe haven "marque" names last year.
"Collectors sought proven artists for investment [in 2011]," he told Bloomberg. It appears that buyers are continuing the trend in 2012.
The May 9 auction also featured the $37.0m sale of Andy Warhol's Double Elvis [Ferus Type].