The 34-year-old reality star showed up with bleached eyebrows for the celebration.
"About last night... #KendallsBDayParty #DontBeScaredOfMyBleachedBrows #ItsForAPhotoShoot," Kim wrote to accompany an Instagram shot of her posing with English fashion model Cara Delevingne.
Both Kendall and Cara, 22, have rocked bleached eyebrows on the catwalk. Kendall for a Marc Jacobs show last autumn and Cara for a Givenchy show in September.
Others snapped at the party included Kim K.'s husband Kanye West and Khloe Kardashian's ex, rapper French Montana.
French (who split with Khloe last month after eight months of dating) posed with Kendall and Kris Jenner, but wasn't seen with Khloe.
He told Us Weekly last week that he still holds out "big-time" hope they would get back together.