Kylie posted videos of them getting ready, including a clip of Sofia in a silver bra and a 60s hairdo.
The Kylie Cosmetics founder also shared a selfie video of herself in a blonde wig, a glittery pink dress and bright rainbow wedges.
She was joined by her model sister Kendall, who was wearing a leopard-print dress and black sandals.
Kendall, Kylie and Sofia joined their friends for a night of karaoke.
Kendall and Tiffany were filmed singing to "Let's Dance," by David Bowie.
RELATED
Jordyn Woods cosies up with RAY J ahead of scathing Keeping Up episode
Kylie Jenner reveals her crazy phone call with Jordyn Woods after the Tristan scandal
Jordyn Woods speaks out as 'KUWTK' set to air Tristan Thompson scandal
While Richie has been friends with Kylie for many years, she has been dating Scott Disick since September 2017.
Over the same weekend, Scott Disick accompanied Kourtney Kardashian, Kim Kardashian and Kanye West on a vacation to Costa Rica with their children.
Kourtney and Scott share three children together and dated for several years.
They have since been co-parenting their three kids while seeing other people.
