Michelle Obama's memoir is coming out in November.
The former US first lady tweeted on Sunday that the book is called Becoming.
Mrs Obama and her husband, former US president Barack Obama, last year reached a joint agreement with Penguin Random House for their respective books. The deal is believed to be worth well in excess of $30m.
Memoirs by former first ladies usually sell well and Michelle Obama's book is highly anticipated. She has never told her story at length. Her only previous book was a 2012 work on gardening, American Grown.
Barack Obama, who has written the million-sellers Dreams From My Father and The Audacity Of Hope, has not yet scheduled his memoir.