Around 5 million people attended WorldPride in New York City over the weekend, surpassing estimates of about 3 million, according to the mayor.
"We saw something amazing this last weekend. Five million people came here for WorldPride. Five million people and there was almost not a single incident," de Blasio said at NYPD graduation on Tuesday. "What I saw was extraordinary efforts by NYPD to keep people safe."
He also noted how the crowds welcomed the NYPD’s presence during the event. Law enforcement, including members of the Royal Canadian Mounted Police, were photographed taking part in the festivities, smiling, holding hands and waving pride flags. Officials said the city collected more than double the trash than it normally collects after New Year's Eve celebrations.
"I saw the people who were here for the event showing their appreciation, applauding the members of the NYPD, thanking them for the extraordinary job they did," de Blasio told the graduating class. "The professionalism on display the last few days, and every day, was extraordinary. And now you get to build on that."
The city hosted WorldPride march on Sunday, coinciding with the 50th anniversary of the Stonewall riots -- an event that helped spawn the modern LGBTQ civil rights movement.
"I think it would be irresponsible of me as we go through World Pride Month not to speak of the events at the Stonewall Inn in June of 1969," O'Neill said at the department's inaugural pride safety briefing. "I'm certainly not going to be an expert of what happened at Stonewall. I do know what happened should not have happened."
The raid at the Stonewall, a gay bar in Manhattan's Greenwich Village neighborhood, unfolded in the early hours of Saturday, June 28, 1969, when NYPD officers stormed into the bar to enforce a discriminatory law that made it illegal to serve alcohol to gay people.
Stonewall and the small park outside are now part of a national monument.
ABC News' Aaron Katersky contributed to this report.