The stark red-on-black "Self-Portrait," measuring almost 9 square feet, is considered a landmark work by the American Pop artist. Created toward the end of his life, it shows the artist, with hair spiked, looking directly at the viewer. It had been estimated to bring up to $40 million.
The acrylic and silkscreen on canvas was one of two red-on-black self-portraits that were first exhibited in London, at the Anthony d'Offay Gallery, in 1986, just six months before Warhol's death.
The other one is at the Guggenheim Museum in New York, donated by Ann and Anthony d'Offay in 1992.
The painting is among seven monumental self-portraits that Warhol painted in 1986. The rest are in museums or in foundations.
A purple "Self-Portrait" was purchased by a European collector last year for $32.5 million.
Another Warhol self-portrait painted from 1963 to 1964 sold for $38.4 million at Wednesday's Christie's auction.
Christie's didn't disclose the identities of Wednesday's buyers.
The auction record for a Warhol is $71.7 million, for "Green Car Crash."
Warhol died in February 1987 at age 58 from complications following surgery.