Palin threw her support behind Republican Karen Handel, the lone woman running for the state's top job.
Clinton, meanwhile, endorsed Attorney General Thurbert Baker in the Democratic race, providing his underdog campaign with a shot of adrenaline.
Palin, the former vice presidential candidate and Alaska governor, said she is "proud to lend my support to a great commonsense conservative woman running for governor this year in the Peach State." She made the announcement through Twitter and Facebook.
Palin has said women activists — or "mama grizzlies" as she calls them — will lead a conservative wave this November. Palin's support for Nikki Haley in South Carolina is credited with helping fuel Haley's Republican primary win.
Palin's support provides Handel with a conservative seal of approval, something she's struggled with in recent weeks. Handel failed to win support from Georgia Right to Life because of her support for rape, incest and the life of the mother exceptions to an abortion ban. And she has been forced to explain her association with Log Cabin Republicans, an organization of gay Republicans. In her endorsement, Palin affirmed Handel's anti-abortion credentials.
Handel has also lagged behind the three other leading Republicans in Georgia when it comes to fundraising and only began running television ads Monday.
State Insurance Commissioner John Oxendine has been the clear money leader in the GOP race, which is almost certain to go into a runoff, necessary in Georgia if no candidate earns more than 50 percent of the vote. There is intense jockeying for one of those two runoff berths.
Handel's opponents wasted no time in going on the attack.
Ben Fry, campaign manager for former state Sen. Eric Johnson, said they "were surprised to see Gov. Palin's endorsement of the most liberal Republican candidate in this race."
But Merle Black, a political science professor at Emory University, said Palin's support for Handel has the potential to be a game changer in the seven-person GOP race, which is still considered up in the air.
"Palin has a very intense, loyal following among Republican primary voters," Black said. "Her opinion — her approval — could really matter to those who are undecided."
He said the effect could be amplified if Palin comes to the state to campaign with Handel, as she did with Haley.
Handel spokesman Dan McLagan said it was unclear if that would happen.
Fresh off her vice presidential defeat in 2008, Palin drew huge, enthusiastic crowds as she swept into Georgia to stump for Republican U.S. Sen. Saxby Chambliss as he faced a runoff battle to return to Washington. Chambliss has credited Palin with whipping up enthusiasm that returned conservatives to the polls in December.
Baker, meanwhile, was trumpeting support from Clinton.
Baker, who is seeking to become the state's first black governor, has been trying to gain ground on former Gov. Roy Barnes, widely considered the front-runner in the Democratic race.
In a release distributed by Baker's campaign, Clinton called Baker "a man made for this moment" who has offered detailed plans to turn Georgia around.
"I think it suggests to voters that we're gaining momentum ever day," Baker told The Associated Press.
"He speaks to some of the things that we are working on here in Georgia that are near and dear to me," Baker said of Clinton. "Like jobs and education."
Clinton's support for Baker comes as little surprise. Clinton hosted a fundraiser for the attorney general in New York late last year.
And it repays a debt from 2008 when Baker was an early supporter of Hillary Rodham Clinton in the Democratic primary. Barnes backed John Edwards.
Baker is one of seven Democrats seeking their party's nomination.