E! News has learned that the two dropped by Therapy, a popular gay bar in New York City, after the One Direction singer's Saturday Night Live gig.
An eyewitness tells E! News that the two "were having a great time" and "for sure looked like they were a couple. They had a blast."
The two spent most of their time in the restaurant area of the hot spot and only stayed for a short while before heading to their next stop of the evening.
The E! reality star was spotted earlier in the night at Styles' side backstage at SNL.
A source tells E! News exclusively that Jenner arrived in the Big Apple for a meeting on Friday, Dec. 5, and added that she and Styles have been in touch for the past several weeks, ever since the American Music Awards.
The source added that although they were both spotted leaving the Gansevoort together over the weekend, the brunette beauty is staying at a different hotel than Styles.
"I've never seen Kendall happier and more fan-friendly," another source told E! News. "They came off the elevator holding hands and then she stood and watched while he posed with fans."
The 18-year-old model told E! News at the AMAs that she and Styles are "friends," adding "he's cool."
Us Weekly was the first to report the outing.