Her debut, called Crumb, will be published in September by Chatto and Windus who called her a "major new food writer".
Tandoh, who was still studying for her degree in philosophy and art history at University College London, lost out to Frances Quinn in the final of the popular BBC show.
She became involved in an online spat with chef Raymond Blanc after he posted a message suggesting she was "so thin" that he doubted her love of food, and also criticised her on-screen tears.
Tandoh later hit back to blast the "lazy misogyny" which she said had been directed towards the show.
She said she was "overjoyed" to be working on the book.
"Although I've only been baking in earnest for a couple of years now, this book will be the product of a lifetime of poring through weekend recipe supplements, scrawling notes in cookbooks, sketching cakes in homework margins and stopping at the window of every bakery I've ever passed," she added.
Her new publisher - which said there was a nine-way battle for her signature - said: "Unfussy yet delectable, this is an irresistible baking book for novices and seasoned bakers alike, written with true passion and flair."