Hilton, meanwhile, celebrated her big day with throwback pics from her 21st birthday on Instagram, including one with Kardashian's mom, Kris Jenner.
"Celebrating my 21st Birthday at #Studio54 with @KrisJenner. ? #BirthdayMemories ?????? #FBF," she captioned the pic, also sharing a pic of the dress that inspired Kendall Jenner's 21st birthday ensemble.