The couple welcomed their third child, a daughter, via a surrogate on Monday, the reality star announced Tuesday.
The baby was born at 12:47 a.m. and weighs 7 lbs., 6 oz.
"Kanye and I are happy to announce the arrival of our healthy, beautiful baby girl. We are incredibly grateful to our surrogate who made our dreams come true with the greatest gift one could give and to our wonderful doctors and nurses for their special care," Kardashian West said in a statement posted to her website. "North and Saint are especially thrilled to welcome their baby sister."
Kardashian West, 37, and West, 40, kept the pregnancy under wraps for some time, but in November, she announced that they were expecting another daughter. They are also parents to daughter North, 4, and son Saint, 2.
"North is really excited about [having a sister]," the "Keeping Up With the Karashians" star told Ellen DeGeneres at the time. "She's so excited. Let's see if it lasts. I did explain to her, 'OK, at four in the morning, when you come in my room, I'm going to have to be with baby sister -- I have to feed her.' We'll see how it goes."