Knicks fans partied like it was 1999 on Monday night, punctuating a dominant run to the NBA Finals with a one-sided sweep of the Cleveland Cavaliers that plunged the Big Apple into jubilant chaos.  

The win ended a 27-year dry spell since their last Finals appearance — and Knicks nation was quick to use the opportunity to make up for lost time.

“The city has been waiting for it since 1999. We’ve been through so many losses and the fans have always stuck close. It’s nice to finally be on the winning side,” Kevin Calle, a 30-year-old human resources manager from New Jersey, told The Post outside of Radio City’s watch party.

“It’s our time. The team is made up of a lot of underdogs. Let’s hope Manhattan makes it out alive tonight!”

While the scene at a Radio City remained under control, Madison Square Garden was plunged into a frenzy where thousands of revelers packed the streets immediately outside The Mecca.

Some scaled lamp posts, while others used brooms to perform a ceremonial “sweep” and hoisted themselves onto elevated ledges.

Within an hour of the Knicks’ clinching win — a 37-point drubbing of the Cavs — fans were chanting, “f—k the World Cup!”

MetLife Stadium is set to host several World Cup matches in June and July.

Many in the mob weren’t alive to see the Knicks play the lat time they made the NBA Finals in 1999, when they lost to the San Antonio Spurs.

“It’s the New York summer. There’s a lot of things going on. The Yankees are doing well, but we got the New York Knicks taking it to the moon. Taking it to the moon!’ Juan Pablo Estupinan, 23, told The Post outside of MSG — while even younger fans crowd-surfed above him.

“We’re split in baseball, we’re split on football, but New Yorkers are united with the Knicks,” said Henry Hunt, 23, from New Jersey.

“The crowd is going nuts. We’ve been waiting for this for a long time.”

Knicks diehards who trekked to Cleveland for Games 3 and 4 threw their own party outside of Rocket Arena — turning it up right in front of despondent Cavs’s fans.

“It’s incredible. I’m on top of the world. There is no stopping the Knicks,” Tara Hochberg, 50, of Long Island, told The Post.

“We want Wemby,” Hochberg and dozens of others chanted, referencing Spurs superstar center Victor Wembanyama. And the same call echoed outside of The Garden as the Knicks await the winner of the Western Conference Finals between San Antonio and the Oklahoma City Thunder.

Even Mayor Zohran Mamdani, who attended Game 2 in the nosebleed seats at MSG, got in on the action poking fun at the decisive win over Cleveland.

“NYC Sanitation, I’d like to report a sweep,” Hizzoner wrote on X.