Bailey joins the elite set of British fashion magazine editors who have crossed the Atlantic for an even more glamorous role, such as Harper's Glenda Bailey (no relation) and Vogue's Anna Wintour.
Bailey said she was "terribly sad" to leave Elle, but had always harboured ambitions to sample glossy magazine publishing in New York.
A spokeswoman from Hachette Filipacchi, which publishes Elle, confirmed that it had started talking to a number of candidates about replacing Bailey. She declined to comment on who they were.
Bailey has worked at Elle for eight years, which she joined as associate editor before coming deputy editor. She became launch editor of Elle Girl and was then promoted to editor of Elle in March 2002.
For 10 years, Elle was published under a joint venture between the French publisher Hachette and Emap, but in August 2002 Hachette bought out Attic Futura and established a UK arm. Emap subsequently lost the battle to retain the rights to publish Elle and Red.
Meanwhile, Hachette Filipacchi has hired former IPC and Emap publisher Rita Lewis as publishing director of women's titles Red and B.
Lewis previously worked as publishing director of IPC's women's portfolio of magazines including Marie Claire, Woman's Journal, 19 and Mizz. Other experience in her 20-year career includes working as managing director of Emap's Women's Group, which was later renamed Emap Elan.
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