The buyer is understood to be Henning Conle, a German-based investor. House of Fraser declined to comment on price or the buyer's identity.
The Fayeds, who recently ended a long feud with Lonrho over the takeover of House of Fraser in 1985, said in July they would float the group's department stores and make non-core disposals.
Northcliffe House is home to Associated Newspapers, publisher of the Daily Mail and Evening Standard, and Scribes West, the club controlled by Terry Venables. Before the rebuilding in 1986, Barkers occupied all seven floors and had 500,000 square feet of selling space. It now retails from 140,000 square feet.