The British writer - whose books include Birdsong and Charlotte Gray - was commissioned by the Fleming estate last year but his identity kept secret.
Devil May Care is set in "several of the world's most thrilling cities" during the Cold War.
The book will be published on 28 May next year to mark the centenary of Sir Ian Fleming's birth.
The Fleming estate announced last year that it had commissioned a "well known and highly respected" writer for the task. Faulks, 54, said his new book is "about 80% Fleming" and admitted being "surprised" that he was the estate's choice.
He said: "I was surprised but flattered to be asked by the Fleming estate last summer if I would write a one-off Bond book for the Ian Fleming Centenary.
"I told them that I hadn't read the books since the age of 13, but if, when I re-read them, I still enjoyed them and could see how I might be able to do something in the same vein, then I would be happy to consider it.
"On re-reading, I was surprised by how well the books stood up."
He added: "I put this down to three things - the sense of jeopardy Fleming creates about his solitary hero, a certain playfulness in the narrative details, and a crisp, journalistic style that hasn't dated."
Faulks said he attempted to "isolate the most essential and the most enjoyable aspects of the books". 
He added: "I found writing this light-hearted book more thrilling than I had expected."
The last of Fleming's 14 books about the secret agent was Octopussy and the Living Daylights, which was published in 1966 - two years after his death.
The first was the 1953 book Casino Royale, made into a film last year with Daniel Craig.
It is not yet known if the new book will be turned into a Bond film.
Corinne Turner, managing director of Ian Fleming Publications, said: "The Fleming family were delighted with the typescript when we received it.
"Sebastian couldn't have written a better book to celebrate Ian's 100th birthday."
Actor and author Charlie Higson was licensed to write books about James Bond's school days. He has so far written four books under the Young Bond banner aimed at younger readers.