Brown, 75, made the announcement on Twitter, the Sacramento Bee said, and followed up with a written statement that ticked off his accomplishments in office and added that he was "here and ready to go."
"At this stage of my life, I can say -- without any hesitation -- that I am prepared and excited to tackle these challenges and the many others that lay before us," Brown said in a written statement. "In fact, there is nothing I would rather do. So today, I have taken out the papers to run for re-election."
Brown, son of Gov. Pat Brown, served two terms as governor in the 1970s and returned to office in 2010 after an unsuccessful campaign for the Democratic presidential nomination against Bill Clinton and a stint as mayor of Oakland.
Brown said California had weathered the recession, a budget crisis and a period of "poisonous partisanship" at the state capital.
The state now faces daunting problems in the form of persistent drought, prison overcrowding and a failure by the federal government to make effective reforms to immigration policy, he said.
Brown will likely run unopposed in the June 3 Democratic primary. The field of Republican challengers includes Laguna Hills Mayor Andrew Blount, former U.S. Treasury Department official Neel Kashkari and State Assemblyman Tim Donnelly, whom the San Francisco Chronicle described as having the backing of the Tea Party movement.