Zohran Mamdani was publicly sworn in as the 112th mayor of New York City during a ceremony at City Hall, becoming the first Muslim and South Asian to lead the largest city in the United States.

Mamdani took the oath of office on the Quran, administered for a second time by US Senator Bernie Sanders, who backed his progressive campaign.

"I promise you this: If you are a New Yorker, I am your mayor. Regardless of whether we agree, I will protect you, celebrate with you, mourn alongside you, and never, not for a second, hide from you," Mamdani told supporters, city officials and family members gathered at City Hall.

"I was elected as a democratic socialist, and I will govern as a democratic socialist. I will not abandon my principles for fear of being deemed radical," he added, reiterating campaign pledges that include universal childcare and rent freezes.

Mamdani said his administration would work to ensure that no New Yorker is priced out of basic necessities, rejecting what he described as governance for either the wealthy elite or a divided city.

He also highlighted the city’s diversity, saying New York’s story would be written by people speaking languages ranging from Pashto and Mandarin to Yiddish and Creole, and worshipping in mosques, synagogues, churches, gurdwaras and temples.

"They will be Palestinian New Yorkers in Bay Ridge, who will no longer have to contend with a politics that speaks of universalism and then makes them the exception," he said.

'Biggest political upset'

Sanders praised Mamdani’s victory as "the biggest political upset in modern American history," saying his promises to make housing affordable, expand public transport and provide free childcare were not radical but "the right and decent thing to do."

Congresswoman Alexandria Ocasio-Cortez said Mamdani’s rise marked a new era for the city, calling him "a mayor for all of us."

The ceremony followed an earlier symbolic swearing-in shortly after midnight.

At 34, Mamdani is the youngest mayor of New York City in generations and the first African-born mayor.

He was born in Kampala, Uganda to Indian immigrant parents and became a US citizen in 2018.