She has been in ad campaigns for Yves Saint Laurent, Jean Paul Gaultier, Louis Vuitton, Versace, Christian Dior, Burberry, Trussardi, Roberto Cavalli, Lanvin, and Chanel. For the Tom Ford 2009 spring eyewear advertising campaign, she was photographed, for the first time, by Ford himself. She was the 2010 face for American fashion brand St. John and Karen appeared with sister Kate in the 2011 H&M Holiday campaign. That same year, she was part of Banana Republic's 2011 Holiday Collection. Her cosmetic advertising credits are YSL's Opium perfume and Kose Cosmetics.