"He devoted his life to building a more just, equal and compassionate world, and we are all better for it," Mayor Michael Bloomberg said in a statement on Mandela's death, adding that flags at City Hall would be lowered to half-staff in his honor.
In Harlem, artist Franco Gaskin, 85, stood in front of a mural featuring Mandela he had painted on a storefront gate almost 20 years ago. He remembered Mandela's 1990 visit.
"It was dynamic, everyone was so electrified to see him in Harlem," Gaskin said. "I idolized him so much. He leaves a legacy that all of us should follow."
Mandela's passing was also marked on the marquee of the famed Apollo Theater, which said, "He changed our world" along with the years of his birth and death.
In 1990, Mandela was greeted by tens of thousands of cheering people as he traveled in a motorcade through black neighborhoods in Brooklyn, and city officials honored him with a ticker tape parade. He made other visits, including after the Sept. 11 attacks and again in 2005 when he was presented the key to the city by Bloomberg. On Thursday, The New Yorker magazine released its cover for next week - a picture of Mandela holding up his right arm in a fist.
"Perhaps once in a generation a man, a movement, and a moment came together on a mission for freedom that is so powerful, so courageous, so just that all the guns and dogs, hatred and violence, deprivation and force that can be mustered cannot turn them back," said David Dinkins, the first black mayor of New York City.
Mayor-elect Bill de Blasio said in a statement he remembered listening to Mandela in Yankee Stadium during his 1990 visit.
"We came to believe in his fight for justice and democracy as if it were our own," de Blasio said.
In his statement, Rev. Al Sharpton said, "Everything humanly possible that could be done to someone other than killing them was done to him, yet he maintained his dignity and his determination. It is almost unthinkable what he endured and yet forgave. He taught us that you have to keep your eye on the prize, and that nothing you suffer is as important as the goals that you are fighting for."
Harlem resident Troy Gibson echoed that thought. Mandela "showed us strength and perseverance, he's taught a lot of people a lot of things."
Gov. Andrew Cuomo said flags on state buildings would be lowered to half-staff in Mandela's honor as well.
"Nelson Mandela refused to accept injustice, fought relentlessly for what was right, and showed that a dedicated person of courage actually can change the course of history," Cuomo's statement said.