The two young stars were romantically linked on and off from 2013 to 2016, when they were spotted ringing in the New Year together on vacation in St. Barts.
They never confirmed their relationship status, but the model was reunited with Styles on Tuesday, December 10 when she appeared on America's "The Late Late Show", which the British singer was guest hosting in place of his absent pal, James Corden.
During the TV get-together, they took part in a game called, "Spill Your Guts or Fill Your Guts", in which participants are dared to either reveal secrets on air, or try strange delicacies from around the world.
And Jenner wasted no time in trying to convince Styles to open up about his songwriting muses for his self-titled debut solo release.
"(I'm) dying to know this," she remarked. "Which songs from your last album were about me?"
"So I'd say track... ummm," he began, before cutting off his sentence and digging into a plate of cod sperm to dodge the question.
Styles again opted to expand his palate as he was asked to rank the solo careers of his One Direction pals, choosing instead to bite into a piece of scorpion.
Meanwhile, the "Sign of the Times" hitmaker took the opportunity to poke fun at Jenner and her family reality show "Keeping Up with the Kardashians", after confessing he once watched an episode of the popular series.
"It was the one where you were eating the salads in the kitchen and then you were all shouting at each other," he cheekily explained - referencing a frequent occurrence in the Kardashian-Jenner households.
Styles isn't the only celebrity tapped to stand in for Corden while he films upcoming movie "The Prom" - Alicia Keys hosted Monday's episode, while Chance the Rapper, Jeff Goldblum, Ken Jeong, and Melissa McCarthy have also signed on to front "The Late Late Show" over the next week.