Deal, a former nine-term congressman from Gainesville, defeated former Democratic Gov. Roy Barnes, who was running to get his old job back after being ousted in 2002.
The win cemented Republican control in the state that had been ruled for generations by Democrats. Republicans claimed every statewide elected office.
"My faith in the people of this great state has been reaffirmed," Deal said as he took the stage to cheers from supporters Tuesday night. "We're going to come out of this recession. We're going to put Georgia back to work."
Barnes said he wished Deal the best in a concession call Tuesday night.
"I am reminded of the words of the Apostle Paul. I have fought the good fight, I have run the good race," Barnes said.
Deal, who will replace term-limited Republican Gov. Sonny Perdue, was buoyed by a strong anti-Washington tide that energized GOP voters upset with President Obama and Democrats in Washington.
The race largely shaped up as a choice between Deal, who pledged to stick to conservative credentials and keep taxes low, and Barnes, who vowed to end teacher furloughs and reduce the state's high jobless rate.
During the campaign, Deal fought off questions about his ethics and his personal finances in a race that featured dueling attack ads and big ad buys by outside interest groups.
Deal was upbeat Tuesday night as returns began to roll in, saying Republicans in Georgia had "an excellent chance of sweeping the entire slate of candidates up and down the ballot this year."
Barnes acknowledged it might be a tough year for his party.
"It's hard for a Democrat to get elected anywhere," he said.
In a Republican state during a year when anger over Democratic leadership in Washington was running high, Deal should have had an easy road to victory, but Barnes kept the Republican on the defensive by questioning his ethics and finances.
Deal and national Republican groups repeatedly sought to link Barnes to Obama, while Barnes worked to demonstrate his independence from Washington.
Barnes pledged his support for an Arizona-style immigration law the Obama administration is challenging in court and also criticized portions of the president's health care overhaul.
In one advertisement put out by the Republican Governors Association, images of Barnes and Obama were overlaid under the title "Roybama."
Deal's consistent message was that Barnes did not deserve a second chance leading the state.
MEANWHILE, BARNES KICKED off the general election campaign before his Republican opponent was even decided.
He aired a TV ad on the day of the runoff in the Republican primary, when Deal defeated former Secretary of State Karen Handel for the nomination.
Needing to gain ground in a state that has voted reliably Republican in recent years, Barnes wasted no time attacking his GOP rival.
He labeled Deal corrupt and suggested he has used his congressional office for personal gain.
The Barnes campaign frequently cited a congressional ethics report released earlier this year that said Deal might have violated rules that govern the conduct of House members.
Deal stepped down from Congress in March to concentrate on the governor's race, effectively ending the congressional investigation.
Deal denied any wrongdoing, but Barnes assailed Deal's ethics in debates and on the airwaves.
Barnes also raised questions about Deal's fitness to oversee the state's finances after it was reported that Deal was so deeply in debt that he'd put his house on the market.
Deal and his wife, Sandra, were left on the hook for a $2.3 million loan after his daughter and son-in-law's sporting goods store failed.
Deal has said he will make good on the debt and has already liquidated about $750,000 in retirement funds to pay it down.
During one debate, Barnes asked voters who they would want to run the state's finances.
The strategy turned off at least one voter, Chris Simon, who manages a family-owned hotel on Tybee Island.
Simon said he was outraged that Barnes made an issue of the loan, and voted for Deal.
"I've helped my children, too, and I didn't think he should have brought that up," said Simons, 63, who says he is a Republican. "I wouldn't have voted for Roy Barnes if he was the only one running because of that."
An early part of Barnes' campaign centered on making amends for putting off voters, particularly teachers, during his first term.
This year he received the backing of the Georgia Association of Educators, which withheld their endorsement in 2002.
ATLANTA RESIDENT Ronny Gutfreund, 32, said he cast his vote for Barnes.
"I just like what his stance on most issues were," said Gutfreund, a radio promoter. "Most of the issues that I researched, he was in line with me on."
In the homestretch of the campaign, Barnes sought to rally female voters, rolling out a tough attack advertisement that suggested that Deal tried to weaken the state's rape shield law when he was in the state Senate in the 1980s and that he voted against toughening domestic violence laws.
Deal disputed Barnes' claims and said the attack on decades-old votes suggested Barnes was desperate for an edge.