The 20-year-old supermodel partied at the Bootsy Bellows 'Red, White and Bootsy' bash in Malibu with the 24-year-old basketball player and her sister Kourtney Kardashian's ex Scott Disick.
A source told PEOPLE: "Kendall and Jordan weren't showing any PDA, one of her girlfriends sat between them."
However, the pair left together, along with Scott, 33.
It was previously revealed that LA Lakers player Jordan is "really into" Kendall but they're trying to keep the romance low-key.
A source said: "He's become really close friends with her group and they're still seeing each other, but it's not a serious situation. They keep things low-key when they're in public, but in private they're very much together and affectionate. He's really into her."
Meanwhile, Kendall recently revealed she wants to married with children within the next 10 years.
The star admires the "chill but extremely fortunate" lives of supermodels Cindy Crawford and Gisele Bundchen and hopes to find herself in a similar happy position in the coming years.
She wrote in a post on her website: I started thinking about my own life in 10 years, which weirdly gave me a strong urge to play 'The Sims'.
"If I were building my perfect world on the game, this is how it would look: I'd have a beautiful, secluded house in Malibu with a gorgeous husband and a couple of kids.
"Seeing models like Cindy Crawford and Gisele live chill but extremely fortunate and blessed lives seems like exactly what I would want."
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