Kardashian West announced the news on her official website, in a post that revealed the weight of the newborn was seven pounds and six ounces.
"Kanye and I are happy to announce the arrival of our healthy, beautiful baby girl," wrote the reality TV star.
"We are incredibly grateful to our surrogate who made our dreams come true with the greatest gift one could give."
She said her other two children, four-year-old North and two-year-old Saint, were "especially thrilled to welcome their baby sister."
