Here's how the whole klan is reacting:
1. Grandma Kris Jenner
Kris wrote, "God is SO good!! I am so excited and thrilled to welcome another precious baby girl to our beautiful, ever growing family. We are blessed beyond belief!"
2. Sister Kendall Jenner
3. Sister Kim Kardashian
4. Sister Khloe Kardashian
5. And finally, Kylie's boyfriend/baby daddy, Travis Scott, posted the cutest tweet:
This post will be updated as more family members react to the joyous news!