Bailey, 40, takes the helm of the newspaper group, which owns three national newspapers and more than 250 regional titles, from February. She replaces Philip Graf, who announced his plans to depart in September.
Despite hiring from outside the newspaper industry, Trinity Mirror has found in Bailey a chief executive with a reputation for making bold and tough decisions. She has not hesitated in closing loss-making magazines such as Melody Maker and Nova and has experience of preparing a business for sale following a management buyout of IPC in 1998 that led to its eventual sale to AOL Time Warner.
The announcement of Bailey's departure surprised many on the IPC board who were told at a board meeting on Tuesday morning. IPC insiders said that a board restructure announced last week was unrelated to Bailey's departure. IPC will announce Bailey's successor early next year, with the board reporting to the Time Inc president, Michael Pepe, in the meantime.
Bailey has been with IPC since 1989 and joined its board in 1994 as its advertising director. She was made chief executive in 1999 after running its TV listings division, tx.
Trinity Mirror faces tough challenges in the national newspaper market after the Daily Mirror saw its circulation drop 2 per cent for the six months to November after a bitter price war with The Sun. The People and the Sunday Mirror also saw circulation declines for the same period. However, the Daily Mirror's sales rose during November following the Paul Burrell revelations.
Bailey said: "Trinity Mirror is an ambitious and successful company with strong businesses, a clear growth strategy and enormous opportunities for further development."
Sir Victor Blank, the chairman of Trinity Mirror, said: "The appointment of Sly is tremendous for Trinity Mirror. She has a proven track record in building businesses and brands, excellent media credentials and will bring extra drive and vigour to both our national and regional newspapers."