Now we know it's because she was involved in a car accident.
On her way to Naomi Campbell's annual Fashion for Relief benefit, Page Six reports that he chauffeured car was involved in a collision.
Thankfully, Kendall attained no injuries, but she was unable to attend the red carpet event with Bella Hadid.
Of course, that doesn't mean that Kendall stayed home. She arrived for dinner at the end of the event to hit the town afterwards.
Thankfully she is okay!