The 27-year-old has decided to commit his future to the Baggies following reported interest from Chelsea in the summer transfer window.
"I'm more than happy to commit my long-term future to the club," Ruddy told the club's official website. "I've thoroughly enjoyed my time at Norwich City – everyone has been very supportive.
"The whole club, the players and staff I have worked with have been fantastic. I've broken into the England squad while at Norwich, and without the opportunity they gave me I wouldn't have been anywhere near it."
Ruddy has the option of adding another year to his deal when it runs out in 2017.