“Tonight Show” host Jimmy Fallon will cross the street from his NBC headquarters to offer support for CBS rival Stephen Colbert on Monday, The Post has learned.

Fallon and a handful of other top comedians are expected to make a cameo at the Ed Sullivan Theater in Manhattan to speak out against the cancellation of Colbert’s top-rated late-night talk show, sources said.

The names of the other comedians could not be immediately learned.

Stephen Colbert announces the cancellation of "The Late Show."
A group of top comedians are expected to rally around Stephen Colbert, after the shocking news of the cancellation of “The Late Show”The Late Show with Stephen Colbert
Sources speculated that Jimmy Kimmel — who is on vacation from taping episodes of ABC’s “Jimmy Kimmel Live!” — would be among Colbert’s famous friends to appear.

Kimmel lashed out at CBS, after learning of the cancellation Thursday, writing on Instagram: “Love you, Stephen. F—k you and all your Sheldons, CBS.”

John Oliver, host of HBO’s “Last Week Tonight,” also spoke out against CBS’ decision to can Colbert.

“Late-night shows mean a lot to me, not just because I work in them, because even growing up in England, I would watch (David) Letterman’s show, which of course was Stephen’s show, and think about what a glamorous world that was,” Oliver told the Associated Press on Sunday.

“So it’s very, very, very sad news. I look forward to seeing what [Colbert is] gonna do next because that man will not stop.”

Jimmy Fallon on The Tonight Show.
Jimmy Fallon, the host of NBC’s “The Tonight Show” is expected to appear on Colbert’s program, along with other top comedians and celebrity friends.Rosalind O’Connor/NBC via Getty Images
Seth Meyers, host of NBC’s “Late Nigh with Seth Meyers,” took to Instagram, writing: “For as great a comedian and host (as) he is, @stephenathome is an even better person. I’m going to miss having him on TV every night but I’m excited he can no longer use the excuse that he’s ‘too busy to hang out’ with me.”

Reps for Fallon, Kimmel, Oliver and Meyers did not respond to requests for comment.

Reps for CBS and Colbert did not comment.

New York Post front page: Sources say CBS canceled Stephen Colbert's show due to low ratings and advertising.
CBS said that the cancellation of Colbert’s show was purely financial.
Colbert, 61, got the ax three days after he took a shot at his bosses at the Tiffany Network over its $16 million settlement with Donald Trump over a controversial “60 Minutes” interview with Kamala Harris.

The settlement comes as the network’s parent Paramount negotiates with the Trump administration regulatory approval for its $8 billion sale to independent studio Skydance.

"The Late Show with Stephen Colbert" marquee at the Ed Sullivan Theater.
The Post reported that “The Late Show” clocked a staggering $40 million annual loss, and according to Puck, it had a budget of more than $100 million a season.Christopher Sadowski
The Post previously reported that the show clocked a staggering $40 million annual loss and Puck News reported that the show had a budget of more that a whopping $100 million a season.

“The show started to slide two years ago,” said a source with knowledge, adding that viewership declines and dips in advertising have impacted all three late-night shows.

Colbert’s show is set to end in May 2026.