The Keeping Up With The Kardashians star, 35, posted a heartbreakingly cute photo of her third child's tiny hand in hers.
The reality TV mama also revealed the tot's name for the first time... Reign!
She wrote: "Madly in love with my little Reign Aston Disick."
Reign was born exactly a week ago on Sunday 14 December.
The date is already an important one in the Kardashian family as it is eldest son Mason's birthday, too!
Reign is Kourtney's third child with long-term partner Scott Disick.
Mason turned five on the day Reign was born, while daughter Penelope is two.
After sharing the picture of Reign on Instagram, Kourtney received plenty of good wishes from her fanbase.
One said: "Omg Reign! I love it."
Another gushed: "So cute. Congratulations Kourtney and Scott!!!"
Madly in love with my little Reign Aston Disick. http://t.co/YpnPTOMGI2— Kourtney Kardashian (@kourtneykardash) December 21, 2014
While most fans seemed to LOVE the name, some weren't so sure...
But what do YOU think?
Tell us what you think of the name Reign in the comment box below and you could win £50!
Celebrity couples who welcomed babies in 2014:
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