The 30-year old Welsh goalkeeper, who has operated as number two behind Ben Foster at The Hawthorns, has extended his stay in the West Midlands until 2016.
"We've seen this season it is important to have a good No.2. Boaz has definitely contributed to our success and stepped up to the plate when Ben Foster was injured," he told the club's official website.
"In the Barclays Premier League it is vital you have a No.2 you can trust in but also a No.2 that can push your No.1.
"Everyone at the club has faith in both of them and, with Luke Daniels, we've got a good set of three keepers who push each other in training and have a good understanding with each other.
"It is testament to the work Dean Kiely has done that we have such a strong unit where all the keepers are happy to support each other no matter who is playing."