The celebrity couple - who already have two-year-old son Saint and four-year-old daughter North - have announced the arrival of a ''healthy, beautiful baby girl'', with Kim confirming the news via her own app.
She announced: ''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.
''North and Saint are especially thrilled to welcome their baby sister.''
Kim, 37, revealed that her daughter was born on Monday (15.01.18) and has confirmed that she weighed seven pounds, six ounces.
The famous beauty - who has been married to the outspoken rap star since 2014 - turned to a surrogate after suffering complications with her own pregnancies, experiencing early-onset pre-eclampsia with North and further troubles during labour with Saint.
Despite this, she previously admitted to finding the surrogacy experience to be even more stressful.
Kim - who has not yet revealed the name of her baby daughter - shared: ''Anyone that says or thinks it is just the easy way out is just completely wrong. I think it is so much harder to go through it this way, because you are not really in control.
''And, you know, obviously you pick someone that you completely trust and that you have a good bond and relationship with, but ... knowing that I was able to carry my first two babies and not my baby now, it's hard for me.
''So, it's definitely a harder experience than I anticipated just in the control area.''
But now, she and Kanye, 40, have finally realised their ambition of extending their family of four.
Speaking previously about the possibility of having more kids, Kim explained: ''I'd just love nothing more than to expand my family and just know that I have this world at home that is safe.''
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