Elizabeth Ashford, Brown's chief deputy press secretary, will leave the administration in April.
Her resignation follows the resignation last month of Brown's press secretary, Gil Duran. That position has not been filled.
In an email, Ashford cited family concerns and said she plans to work as a communications and public affairs consultant.
"I'm indebted to the Governor and Anne (Gust Brown) for the opportunity to work here over these incredible two years," she wrote.
Ashford, 38, was chief deputy communications director and chief deputy Cabinet secretary in former Gov. Arnold Schwarzenegger's administration, and she later worked as a spokeswoman for BP.
Brown's communications office will be down to three people when Ashford leaves. That is the same number it had during the first month of Brown's term, before the administration staffed up.
"After more than fulfilling her two-year commitment to the administration earlier this year -- and recently tying the knot with her now LA-based husband -- we knew we'd lose Elizabeth soon," Evan Westrup, Brown's deputy press secretary, said in an email. "We're sad that day has come, but we're incredibly grateful for her service."
PHOTO CREDIT: California Gov. Jerry Brown explains his budget proposal during a news conference at the Capitol in Sacramento on Thursday, Jan. 10, 2013. Randall Benton / Sacramento Bee