Caitlyn, who was previously known as Bruce Jenner, took to Twitter and shared a picture of the birthday girl sitting in front of her cake, reported E! Online.
"Happy birthday to my little angel @KylieJenner. Officially my last adult, my work is done. Love you, proud of you," Caitlyn, 65, captioned the photo.
Kris Jenner also took to Instagram to wish her daughter.
"Happy Birthday to my little shining light in my heart and my life! You are one of the kindest, most loving, generous, sweetest, smartest, most loyal, brightest, most giving, infectious, hard working, bravest, dearest, hilarious and messiest girls I know.