In a 7-0 ruling, the Illinois high court struck down Monday's Appeals Court ruling that Emanuel failed to meet residency requirements, which require mayoral candidates to live in Chicago for at least one year before the election.
Today's ruling ensures that Emanuel's name will be on the ballot when early voting begins next Monday.
Even before issuing today's decision, the Illinois Supreme Court had already granted an emergency request by Emanuel to stop the city board of elections from printing ballots without his name on them.
The Board had been poised to begin printing the ballots in the next few days. The order made it clear that any ballots printed while Emanuel's appeal to the Supreme Court is pending must include his name.
"I have no doubt that, in the end, that we will prevail in this effort," Emanuel, the frontrunner in the race, said when his campaign filed its appeal.
The appellate court's surprise 2-to-1 decision on Monday had reversed earlier rulings by a Cook County judge and the Chicago Board of Election Commissioners that approved the legality of Emanuel's mayoral bid. Emanuel is a longtime Chicagoan, representing part of the city as a Congressman, but was away when he was President Obama's Chief of Staff.
The appeals court ruling distilled the debate over Emanuel's residency into two questions: whether Emanuel had "resided in the municipality" for at least one year as mandated by city code, and if not, whether he qualified for an exemption.
On the first issue, Judge Thomas Hoffman ruled that Emanuel did not fulfill residency requirements as intended by law.
"Reside generally means, among other things, 'to dwell permanently or continuously,' or to 'have a settled abode for a time,'" wrote Hoffman in the majority opinion. "We believe ... that the phrase 'resided in' as used in the Municipal Code requires actual, not constructive, residence."
Municipal code provides an exemption to the residency requirement for an "elector or spouse" who has left the precinct or district on "business of the United States or of this state."
But Hoffman ruled that that provision only applied to voters, not candidates for public office. "We agree ... that this exception applies to him," he wrote. "We disagree, however, with his position that the exception saves his candidacy. In our view, the exception ... applies only to voter residency requirements, not to candidate residency requirements."
From January 2009 through October 2010, Emanuel physically resided in Washington, D.C., where he worked daily at the White House.
Dissenting Opinion Favors Emanuel Residency
Emanuel told reporters Monday that a strongly-worded dissenting opinion, written by Judge Bertina Lampkin, added to his confidence for a successful appeal.
Lampkin wrote that the candidate's intentions, borne out in the undisputed facts of the case, should definitively resolve the residency question.
"The candidate never formed an intent to either change or terminate his residence in Chicago, or establish his residence in Washington, D.C., or any place other than Chicago," she wrote. "Because the candidate had established his Chicago residency, it is presumed to continue until the contrary is shown, and the burden of proof is on the person who claims that there has been a change."
Emanuel has been the frontrunner in the race to succeed long-time Chicago Mayor Richard Daley.
The latest Chicago Tribune/WGN poll shows Emanuel with a two-to-one lead over his closest challenger, former U.S. Sen. Carol Moseley Braun D-Ill.. Forty-four percent of likely voters said they'd vote for Emanuel while 21 percent expressed support for Braun.
ABC News' Jake Tapper contributed to this report.