"There is no God. No one directs the universe," he writes in "Brief Answers to the Big Questions."
"For centuries, it was believed that disabled people like me were living under a curse that was inflicted by God," he adds. "I prefer to think that everything can be explained another way, by the laws of nature."
Hawking suffered from amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder also known as Lou Gehrig's Disease, for most of his adult life.
The scientist died while still working on the book, which his family and colleagues finished with the help of his vast personal archives.