Kimmel had taken a moment during the show to thank those who pay to watch feature films at a movie theater. Followed by an applause from the audience of stars, Kimmel said he wanted to do more than clap for them.
He then showed night-vision video of several people sitting in a theater room at the TCL Chinese Theatre who were expecting to watch a sneak preview of the movie "A Wrinkle in Time."
He gathered stars like Ansel Elgort, Mexican film director Guillermo del Toro, "Wonder Woman" actress Gal Gadot and "Black Panther" actress Lupita Nyong'o and asked them to accompany him to surprise the fans, who were being secretly recorded.
The stars stood outside theater 6 with baskets of candy, a 6-foot sub and a hot dog cannon. Gadot and Kimmel led the way to the packed room, which quickly erupted in cheers and a standing ovation as the pair walked in.
The stunt was followed by video of the Oscar audience of celebs yelling "thank you" from the movie screen.
The celebrities then emerged from the stairs with loads of snacks for fans, who also got to shake hands and hug many of the stars.
"I saw Lupita Nyong'o and I was like, 'Oh my God!' I looked over and it was Lin-Manuel Miranda, and he was like, 'have a Starburst,'" laughed two excited fans.