Democrat Ed Koch, who oversaw the city during some of its darkest years, had been in and out of hospital in recent months.
Ed Koch became mayor in 1978 when New York was graffiti-marred and crime-ridden, and was credited with saving the city from bankruptcy in the 1980s.
He served three terms and afterwards remained active and popular, practising law, writing, and hosting a chat show.
Ed Koch had been battling various health problems, including heart disease.
He was taken to hospital at the start of the week suffering from shortness of breath, and was moved to intensive care on Thursday for the closer monitoring of fluid in his lungs and legs, according to the Associated Press.
Ed Koch died at 02:00 a.m. at the New York-Presbyterian hospital, his spokesman George Arzt said.
His funeral will be held at Temple Emanu-El in Manhattan on Monday.
Ed Koch was mayor of New York City for three terms, from 1978 to 1989, and is remembered for frequently asking residents: “How’m I doing?”
His tough fiscal policies are credited with helping the city climb out of near-financial ruin and improving the subway service, but his critics say they also led to an increase in homelessness and racial tensions.
He was known for being outspoken and combative.
“I’m not the type to get ulcers,” he once quipped.
“I give them.”
Ed Koch was a US congressman from 1968 until he ran for city hall.
Even when he left office in 1990, there was no thought of retiring.
Ed Koch worked as a lawyer, made regular appearances on television and wrote a number of books.
18wejPD9eCcImage source: Wikimedia Commons President-elect Donald Trump celebrated his election victory at the Ultimate Fighting…
Millions of voters across the US chose to return Donald Trump to the White House…
Donald Trump declares victory in the US election as he addresses jubilant supporters in Florida.…
Stocks around the world are rising as Donald Trump appears to be on the cusp…
Donald Trump has won Pennsylvania, North Carolina and Georgia and taken a lead over Kamala…
Quincy Jones, the celebrated musician and producer who worked with Michael Jackson, Frank Sinatra, Ray…