In announcing his decision Wednesday, Brown said he hoped to pursue private-sector opportunities while not discounting a future bid for office, the Boston Globe reported.
"I've decided, with my wife's blessing, that I will not be running for governor of Massachusetts in 2014," Brown said on WBZ, Boston.
After he lost his re-election bid to Democrat Elizabeth Warren in 2012, Brown took a job with a Boston law firm and a post as a Fox News commentator.
"I have been fortunate to have private sector opportunities that I find fulfilling and exhilarating," Brown said on his Facebook page. "These new opportunities have allowed me to grow personally and professionally. I want to continue with that process."
Brown told WBZ he'd back Charles Baker, the party's 2010 gubernatorial nominee, if the Swampscott Republican decides to make a second run, but raised concerns about Baker's voter appeal.
"Is he Mr. Personality? No," Brown said. "Everyone knows that, he's not."
Brown's announcement came as Republicans in Massachusetts and elsewhere fumed at what they called Brown's office-shopping, the Globe said. His water-testing for various offices frustrated the state GOP's efforts to develop a strong ticket next year.
"Is anyone really surprised?" GOP strategist Jason Kauppi asked after Brown's announcement. "I think Senator Brown was probably having some fun with all of it, keeping people guessing."