Rahm Emanuel has been the clear front-runner in the race ever since he resigned as White House chief of staff [EPA]

Rahm Emanuel, the former White House chief of staff, has been elected mayor of Chicago, easily overwhelming five rivals to take the helm of the third-largest US city.

Emanuel was declared winner on Tuesday night after capturing the majority needed to avoid a runoff.

The former Obama aide, who would be the Windy City's first Jewish mayor, held 55 per cent of the vote with 86 per cent of results from district neighbourhoods counted, the Chicago elections board reported.

"We're cautiously elated," Robert Cole, Emanuel campaign co-chair, told NBC Chicago.

The other major candidates - former Chicago schools president Gery Chico, former US Senator Carol Moseley Braun and City Clerk Miguel del Valle – had hoped to force a runoff but were no match for Emanuel's juggernaut.

"Chicagoans feel Chicago is a difficult city to rule," said Ken Janda, professor emeritus of political science at Northwestern University.

"You've got to be a guy who says no. And Emanuel is seen to be a guy who is tough and can say no."

Emanuel has been the clear front-runner in the race ever since he resigned as White House chief of staff and moved back to Chicago in October.

The 51-year-old, who was born in Chicago and served a slice of the city for years in the US House of Representatives, triumphed over objectors at the city's elections board and again at the county court.

Emanuel was also favoured because he has such a high-profile support. Obama - who remains wildly popular in his adoptive hometown of Chicago - gave Rahm a glowing endorsement.

And former president Bill Clinton flew to the heavily Democratic city last month to campaign for Emanuel, who once served as his senior adviser.