The first car accident Kylie Jenner ever had just scored her another milestone -- her first big fat lawsuit.
Kylie's being sued for the 3-car pileup she allegedly started back in August 2013 -- just 18 days after her 16th birthday. TMZ broke the story ... Kylie was driving a Mercedes G-Wagon when a witness says she slammed into the back of a car stopped in traffic.
According to the lawsuit, Kylie started a chain reaction ... hitting a Toyota ... which then rear-ended a Subaru. The woman who was driving the Subaru is suing her for being a negligent driver. She's also suing Kris Jenner because they believe she was the registered owner of the Mercedes.
The woman's attorney tells us she suffered injuries to her neck and back.
Relevant note: Kylie was involved in another accident almost a year later -- this time in a Range Rover -- though it wasn't clear whether she caused that one.