Humes, 54, of San Francisco, was an executive secretary to Brown in the governor's office and was chief deputy attorney general when Brown was attorney general. He will fill the vacancy created by the retirement of Justice James Marchiano, the governor's office said.
Humes is the first openly gay justice to serve on the California Court of Appeal.
The appointment was one of six judicial appointments announced Saturday, including two on the First District Court of Appeal.
Other than Humes, Brown named Therese Stewart, chief deputy city attorney in San Francisco, to the court's second division. She argued on behalf of San Francisco in litigation against Proposition 8, California's now-invalidated same-sex marriage ban, the governor's office said.
Like Brown, both Humes and Stewart are Democrats.
The appointments both fill vacancies created by retirements, Brown's office said. The pay for each position is $207,463 a year. The positions require confirmation by the Commission on Judicial Appointments.
PHOTO: Jim Humes, right, talks to Bee reporter David Siders in January 2011. Hector Amezcua / Sacramento Bee file, 2011.