The now legal Keeping Up With the Kardashians
star went blonde for her big day, surrounded by her famous family. Her sisters Kendall Jenner, Kim Kardashian, Kourtney Kardashian, and Khloe Kardashian were all in attendance at the big bash, as well as Kanye West and Khloe's reported boyfriend, NBA star James Harden
. Caitlyn Jenner was also at the festivities, Kylie captioning this group pic, "MY GIRLS. party night. #18@12."