Emanuel needed 50 percent plus one vote to avoid a runoff against his nearest competitor and handily won that and more to propel him into the office owned by the Daley family for 43 of the last 56 years.
With nearly 94 percent of precincts reporting, Emanuel, former chief of staff for President Obama, had 301,207 votes or 54.94 percent. His nearest rival, attorney Gery Chico, had 133,690 votes or 24.39 percent. Former U.S. Sen. Carol Moseley Braun had just 48,092 votes or 8.77 percent and was running fourth.
Jubilant Emanuel supporters partied at Plumbers Union Hall while awaiting their candidate's victory appearance.
Emanuel pledged "to make a great city even greater." He called his election "a victory for all those who believe we can overcome all the old divisions that have held Chicago back. It is easy to find differences. We cannot allow them to become divisions. … We will move forward together as one city with one future. … I am more convinced than ever we can meet the great challenges before us."
Emanuel called for safer streets, better schools and more jobs.
"The plural pronoun 'we' is how we're going to meet the challenges of tomorrow."
In his concession speech, Chico, a former Daley chief of staff, pledged to give Emanuel his full support.
"I want with all my heart for Emanuel to be a success as mayor," Chico said.
Braun and Chicago City Clerk Miguel del Valle, who ran ahead of Braun, also conceded.
The election is one of the few in the last half century without a Daley on the ballot and the first wide-open contest in more than two decades. It was also the first time mayoral candidates ran at large.
Mayor Richard M. Daley, the city's longest-serving mayor, announced late last year he would not seek re-election, triggering a stampede that initially saw more than a dozen candidates vying for his fifth-floor City Hall office. That number was whittled to six.
The Chicago Board of Election Commissioners said turnout was disappointingly low at less than 40 percent. Voting started out slow Tuesday morning as snow and freezing temperatures encouraged voters to stay home.
The Chicago Tribune reported few glitches: a drunk election judge and a polling place in a church that opened late because the pastor overslept.
Polls closed at 7 p.m.
Some precincts were so quiet, election judges cheered when two voters walked into Warren Park on the North Side.
"It should be packed at lunch hour and it's not," Kathy Holdren, one of six judges in the precinct, told the Tribune. "It goes faster if we have more people."
WBBM-AM, Chicago, said two voters drove up to another North Side precinct in a Bentley -- with Michigan license plates.