He became the first New York City mayor to take his oath using the Quran.
Mamdani, the city’s first Muslim mayor, used a Quran once owned by his grandfather for the ceremony, held by his wife Rama Duwaji.
The inauguration took place in an abandoned subway station located beneath city hall.
Mamdani stated the location symbolised a city that dared to build great things to transform working people's lives, an ambition he believes should not be confined to the past.