A Street Cat Named Bob, the original book about how Bob helped busker James Bowen turn his life around, has sold more than a million copies in the UK.
Work on the film will begin version in October.
Luke Treadaway, who found fame on stage in The Curious Incident of the Dog in the Night-Time, will play Bowen.
The movie will also star Treadaway's real-life girlfriend, actress Ruta Gedmintas, and be directed by Roger Spottiswoode, who made Tomorrow Never Dies.
The film will be based on the book, which tells the story of how Bowen, then a recovering drug addict, found an injured Bob in his sheltered accommodation in 2007 and nursed him back to health.
The pair became inseparable and Bowen credits the scarf-wearing cat with aiding his own recovery.
A Street Cat Named Bob: And How He Saved My Life was published in 2012, and there have since been five further books.
A film has been in the pipeline for several years, and in 2013 Bowen told the BBC: "Bob changed my life and if they make a movie about us, that will just be the ultimate rags-to-turning our life somewhere better."
The heart-warming story of a cat named Bob and his owner, which has already spawned a series of best-selling books, is to be turned into a major film.