W H Allen is to publish a biography of Prince Charles by TIME magazine editor at large Catherine Mayer.
Publishing director Ed Faulkner acquired world rights to Charles: The Heart of a King through Ed Victor at Ed Victor Ltd.
Mayer wrote a global cover story for TIME in November 2013 on Prince Charles.
Faulkner said: "Catherine Mayer is one of the best writers at work in Britain today. As Prince Charles gradually takes on more of the duties of the monarchy, and balances these against his charitable empire and other interests and initiatives, this book will be a hugely significant publication, guaranteed to set the news agenda alight and radically define our understanding of our future king."
Mayer said she was "drawn to write a profile of the Prince by the gap between his public image and the person I suspected he might be".
She continued: "The Prince has proved complex and compelling, a philanthropist and activist with a substantial body of achievement who is routinely underestimated, a thought leader on climate change who lives in places, a public figure that remains largely unknown.
"In writing this book, I aim to unravel these paradoxes and show the scale and scope of his impact on public life."
The book cover will feature a portrait of Prince Charles by photographer Nadav Kander.
Charles: The Heart of a King will be released in hardback in March 2015.