Webb, who joined Yahoo's board in February 2012, was serving on an interim basis after Fred Amoroso resigned as chairman in April.
Yahoo, which has weathered a series of management and board changes in the past two years, is adding tools and services to help woo users and advertising dollars under Mayer, who joined the Sunnyvale, California-based company in July 2012.
"Maynard Webb's leadership and guidance have been an invaluable part of our board since he joined it in 2012," said Anne Espiritu, a spokeswoman for Yahoo. "We are honored that Maynard will continue to serve as chairman of the board."
Webb is a longtime Silicon Valley executive. He was CEO of LiveOps, a provider of cloud contact center services, from 2006 to 2011. Prior to his time there, Webb served as the chief operating officer of online marketplace EBay Inc. (EBAY)
As part of Mayer's push, she has spent more than $1.2 billion to buy at least 20 startups in a shopping spree focused on bringing top engineering talent back to Yahoo.
Earlier this month, Yahoo bought Rockmelt, a developer of Web-browsing software. The company in May also said it agreed to acquire blogging platform Tumblr for $1.1 billion.