Styles, 19 and Kendall, who recently denied they were dating, were swarmed by fans as they exited the Gansevoort Hotel in New York City to enjoy breakfast, reported Us magazine.
Styles was immediately recognised by a group of young girls as security tried to escort him out of the building.
Kendall, 18, who split from her high-school boyfriend Julian Brooks earlier this year, appeared to be startled by the commotion and got caught up in the frenzy as she walked a few feet away from Styles.
The budding model, who is Kim Kardashian's half-sister, previously said, "There is no story. We're friends. He's cool, yeah, he's cool.