The art, painted by Lucian Freud just prior to the birth of Moss' daughter, will go up for bids Feb. 9 at Christie's as part of its Post-War and Contemporary Art sale, Britain's Daily Mail reported Friday.
With the exception of a portrait of Queen Elizabeth, Moss' painting may be the best known of the 81-year-old artist's works.
Freud, grandson of renowned psychiatrist Sigmund Freud, typically paints portraits of friends and usually not models, who he said are "hardened ... because they've been looked at so much."
Moss, whose daughter Lila Grace is now 2, suggested the portrait, which usually takes six months to a year of sittings.
The painting, titled "Naked Portrait 2002," was purchased by a private collector soon after it was completed.
LGBT community has 'bullied the American people': Bachmann
Attkisson leaves CBS News, reportedly over network's 'liberal bias'