S. J. Watson's first novel, Before I Go To Sleep, became a phenomenal international success and has now sold over 6,000,000 copies worldwide. It won the Crime Writers' Association Award for Best Debut Novel and the Galaxy National Book Award for Crime Thriller of the Year. The film of the book, starring Nicole Kidman, Colin Firth and Mark Strong, and directed by Rowan Joffe, was released in September 2014. S. J. Watson's second novel, Second Life, a psychological thriller, was published to acclaim in 2015.

S. J. Watson was born in the Midlands and now lives in London.