LONDON—Eric Clapton is now a new kind of record holder. The guitarist's chromatic painting by Gerhard Richter, "Abstract Painting (809-4)," sold at Sotheby's contemporary art evening auction in London on Friday for £21.3 million $34.2 million—more than anyone has ever paid at auction for a work by a living artist.

The record unseats Jasper Johns, whose "Flag" sold for $28.6 million at Christie's two years ago.

It...