Kourtney Kardashian, Scott's ex and the mother of his three children, was also in attendance, posing with Kylie while rocking a burnt orange silk shirt dress on Instagram with the caption, "Minnie and Tink, before your eyes." The pair posed in front of an ice cream truck that reads, "Please Wash Your Hands."
True Thompson, the 2-year-old daughter of Khloe Kardashian, shared a snack with Stormi in one clip as Khloe can be heard in the background saying, "Come on, Chi Chi, let's go," referencing Kim Kardashian West's daughter, Chicago.
Though Scott didn't share photos from the event, he did post a pic of his birthday present from Kris Jenner, writing, "Thank you so so much @krisjenner for the most over the top mountain bike I have ever seen! #trek."
The gathering comes after Scott and his ex, Kourtney, returned from a getaway to Utah with their three kids last weekend. In addition to the festivities, Scott and his girlfriend of three years, Sofia Richie, have recently split, according to multiple reports.
Earlier this month, Scott checked himself in and out of a Colorado rehab facility. At the time, a source told ET that both Sofia and Kourtney were both "big proponents" of having Scott enter rehab once again. ET's source said Scott "has struggled with these issues for a while and although he was previously doing well, it was time for him to get help again."