The 35-year-old singer reacted Sunday on Instagram to the 19-year-old reality star channeling her "Dirrty" music video to celebrate Halloween with boyfriend Tyga.
"'YAASSSSSS'.....Killin it @kyliejenner yes to dirrty 2016!! Get it girrrl!!!" she captioned a re-grammed photo of Jenner, adding applause and other emojis.
Jenner went all out to replicate Aguilera's look from the 2002 video, wearing a blonde and brunette wig, blue contact lenses and fake nose and labret piercings. She shared several posts on social media, including a close-up of her face.
The Keeping Up with the Kardashians star and Tyga partied with friends Saturday at Bootsy Bellows nightclub in Los Angeles. Tyga dressed as rapper Juelz Santana, while Jenner's half-sister Kourtney Kardashian went as a zombie bride.
Kardashian also celebrated an early Halloween with her daughter, Penelope Disick, and close friends last week. The 37-year-old reality star dressed as an evil queen, while 4-year-old Penelope went as Frankenstein's bride.
"Halloween has always been one of my favorite holidays," she wrote on her website at the time. "I still love dressing up just as much as I did when I was younger. The best part of Halloween is finding the perfect costume."
Jenner, Kardashian and their family recently returned on Keeping Up with the Kardashians on E!. The series premiered part two of Season 12 on Oct. 23, and airs Sundays at 9 p.m. ET.