Chambliss' win over Jim Martin ended Democratic hopes of securing a filibuster-proof majority, which would make it easier to pass legislation.
In his run-off campaign, Chambliss reminded Republican voters that electing Martin would put Democrats one seat closer to giving a "blank check" to President-elect Barack Obama. Democrats already hold a solid majority in the House of Representatives.
"You have delivered a message that a balance in government in Washington is necessary and that's not only what the people of Georgia want, it's what the people of America want," Chambliss told supporters Tuesday evening after Martin called to concede the race.
Democrats won at least seven seats held by Republicans in the general election, putting the balance of power for the incoming Senate at 58 Democrats and 41 Republicans, including the two Independents who caucus with the Democrats.
But one race remains to be called in Minnesota between incumbent GOP Sen. Norm Coleman and Democrat Al Franken as the state completes a mandatory recount.
The Georgia race had attracted some of the biggest names from both parties, including Republican presidential candidate John McCain and running mate Sarah Palin campaigning for Chambliss and former President Bill Clinton and his vice president appearing on behalf of Martin.
According to unofficial results from the Georgia Secretary of State, Chambliss won 57.4 percent of the vote while Martin won 42.6 percent with 97 percent of precincts reporting.
The general election numbers were much closer, with Chambliss winning 49.8 percent of the vote and Democrat Jim Martin 46.8 percent, according to official results from Georgia's Secretary of State. Libertarian candidate Allen Buckley won 3.4 percent of the vote. The state mandates a run-off if a candidate does not win 50 percent plus one vote.
The disparity between the run-off tally and the Nov. 4 vote may be attributed to poor turnout among the state's Democratic voters, who showed up to vote for Mr. Obama but did not turn out again Tuesday.
"For a lot of African-American voters, the real election was last month," said Merle Black, an expert in Southern politics at Emory University, according to the New York Times. "The importance of electing the first African-American president in history generated enormous enthusiasm. Everything else was anticlimactic."
Obama did not campaign in Georgia for Martin but he did record a radio ad for the Democrat and left his campaign offices open.
In Minnesota, the state has recounted 92.69 percent of the ballots, according to the Secretary of State's office. Unofficial results show Democrat Franken holding a slight lead with 41.47 percent compared to Coleman's 41.38.