(CNN)Kylie Jenner kept her pregnancy private, but on Sunday she shared the news of her baby's birth with the world: It's a girl!
Kylie Jenner welcomes baby girl
The reality TV star made the big announcement on social media Sunday, saying she gave birth on Thursday to a "beautiful and healthy baby girl."
"Pregnancy has been the most beautiful, empowering, and life-changing experience I've had in my entire life and I'm actually going to miss it," she told her millions of followers.
This is Jenner's first child.
Jenner, 20, has not publicly identified the baby's father.
She is known to be in a relationship with rapper Travis Scott.
A makeup mogul and reality star, Jenner has kept her pregnancy under wraps throughout, refraining from acknowledging it publicly or posting about it on social media, a unique move for a member of one of the internet's most social-friendly families.
Sources close to the family confirmed she was expecting to CNN in September.
"My pregnancy was one I chose not to do in front of the world," Jenner said on Sunday. "I knew for myself I needed to prepare for this role of a lifetime in the most positive, stress free, and healthy way I knew how."
Jenner followed the Tweet with a video published to her YouTube channel showing intimate details of her life over the last last nine months. There's no news yet on the newborn's name.
CNN's Sandra Gonzalez contributed to this story.