In a victory for the Democratic Party’s progressive wing, Mr Mamdani defeated former governor Andrew Cuomo and Republican Curtis Sliwa.
Mr Mamdani must now navigate the unending demands of America’s biggest city and deliver on ambitious — sceptics say unrealistic — campaign promises.
— Zohran Kwame Mamdani (@ZohranKMamdani) November 5, 2025
With the victory, the democratic socialist will etch his place in history as the city’s first muslim mayor, the first of South Asian heritage and the first born in Africa.
He will also become the city’s youngest mayor in more than a century when he takes office on January 1.
Mr Mamdani’s unlikely rise gives credence to Democrats who have urged the party to embrace more progressive, left-wing candidates instead of rallying behind centrists in hopes of winning back swing voters who have abandoned the party.
He has already faced scrutiny from national Republicans, including President Donald Trump, who have eagerly cast him as a threat and the face of what they say is a more radical Democratic Party.
The contest drove the biggest turnout in a mayoral race in more than 50 years, with more than two million New Yorkers casting ballots, according to the city’s Board of Elections.
At his victory party in Brooklyn, Mr Mamdani’s supporters cheered and embraced, some tearfully, after The Associated Press called the race.
Campaign posters flew through the air, as one person hoisted the official flag of New York City and Bad Bunny played from the speakers.
Andrew Cuomo was criticised for running a negative campaign (Richard Drew/AP)
Mr Mamdani’s X account posted a video of a subway train pulling up to City Hall station, with an announcement that said, “The next and last stop is City Hall.”
His grassroots campaign centred on affordability, and his charisma spoiled Mr Cuomo’s attempted political comeback.
The former governor, who resigned four years ago following allegations of sexual harassment that he continues to deny, was dogged by his past throughout the race and was criticised for running a negative campaign.
There is also the question of how Mr Mamdani will deal with Mr Trump, who threatened to take over the city and to arrest and deport him if he won.
Mr Mamdani was born in Uganda, where he spent his early childhood, but was raised in New York City and became a US citizen in 2018.