"He was there. I think he's been a couple times, but that was the first time I was there that he was there. And I literally left early," she revealed. "I just saw Once Upon a Time in Hollywood and it was so good and he, like, gets better with age. So I was like, 'I gotta go.'"
As for why she made a quick escape, Jenner told Fallon that her nerves simply got the best of her.
"Isn't there a saying like, 'Don't ever meet your superhero' or whatever?'" she questioned of Pitt, who she said she'd like to set up with Rihanna during a drinking game on the show. "I don't know. I just, like, love him so much. I'm like, 'I'm just gonna leave it at that and leave.' I get nervous."
Despite Jenner's nerves, a source at the service told ET that Pitt appeared "amazed by the atmosphere and love" and "made sure to take as many pictures with everyone who asked."
During her appearance, Jenner also discussed her family, even opening up about her new nephew, 3-month-old Psalm West.
While all is well now, Jenner revealed that, after being out of town for Psalm's birth, she "actually got kidnapped" by her sister upon her return.
"Kim, like, made me come to her house and, like, help her pick a name. And, like, it was this whole thing," Jenner said of her older sister, who was choosing between a few potential picks. "She's would not let me leave the house until we figured out a name. And then ended up going for a name that I didn't care for as much. Like, I think they were all really beautiful, but I was kinda rooting for another name."
"... [Kim] was home alone I think and she was like, 'Come over. Help me figure it out. I just need someone here,'" Jenner continued. "I feel like I was the only person that was available. And then, yeah, she ended up going with Psalm."
Kendall went on to describing sitting at Kardashian West's house "for hours" and being forced to watch Five Feet Apart, which she called "the saddest movie of all time."
"I cried my eyes out and I'm leaving the house crying... It was so sad and I left there just, like, a wreck," she said. "And the name didn't even get chosen!"