Crist, a Democrat, made the announcement in a tweet.
Crist did not make clear what role Messina would have on his 2014 campaign.
According to The Miami-Herald’s Marc Caputo, Messina will serve as more of a senior adviser and not a campaign manager.
Messina downplayed a report of taking on the campaign manager position in a recent interview with the newspaper.
"Gov. Crist was obviously very helpful to the 2012 reelect. He did whatever we asked and was very helpful giving strategic advice,” Messina told the Herald.
Crist is challenging incumbent Gov. Rick Scott (R) in November. Crist served as Florida’s governor from 2007 to 2011, mostly as a Republican. He left the GOP in 2010 after losing a Senate primary to Sen. Marco Rubio (R-Fla.).