The British couple's account of how the little girl vanished on a family holiday to Portugal in 2007 was due to hit the shops on April 28, just before the fourth anniversary of her disappearance.
But publishers Transworld postponed the release date by a fortnight after it was announced that Prince William would marry Kate Middleton in Westminster Abbey in London on April 29.
The book, which is being written by the McCanns themselves and is simply entitled Madeleine, will now be published on May 12, the missing child's eighth birthday.
All proceeds from sales of the book will go to the McCanns' official fund to look for Madeleine, which had been in danger of running out in 2011.
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McCann family spokesman Clarence Mitchell said: "The publication date for Madeleine has now been moved on to May 12 2011 in the light of the royal wedding and the subsequent media coverage that will generate.
"Kate and Gerry are very happy with the new date, as are the publishers, and it will still be very much tied into the fourth anniversary of Madeleine's disappearance."
Madeleine was nearly four when she vanished from her family's holiday apartment in Praia da Luz in the Algarve on May 3 2007 as her parents dined with friends nearby.
Despite a massive police investigation and huge publicity worldwide, she has not been found.
The official Portuguese inquiry into Madeleine's disappearance was formally shelved in July 2008, although private detectives employed by the McCanns have continued the search.
