The actor's rep confirmed the news to People magazine Monday, about a week after the couple celebrated their four-year anniversary on May 22.
"I was always the guy who thought I'd never get married because [I thought], 'There's never going to be one woman worth giving up all the others,'" Hammer told People in 2010. "But she knocked me off my feet."
Hammer, 27, is best known for his roles in The Social Network, Mirror Mirror and J. Edgar. Chambers, 31, is a television host and actress. The duo also owns and runs Bird Bakery in San Antonio, Texas.