The mum-of-three, 36, posted the cute snap on Saturday (16 May) and it's only the SECOND time she has chosen to show his face to the world.
Although the Kardashians aren't known for being private, Kourtney has been shielding her little one from the public... But we're SO glad she shared this heartmelting snap!
Alongside the picture, the KUWTK star wrote: "My RAD little bunny."
In the photo, five-month-old Reign is snuggled in a car seat wearing a tiny woollen hat with rabbit ears.
And we think he looks the spitting image of older siblings Penelope, two, and Mason, five.
Kourtney shared her first photo of her son earlier this year, and he's clearly going to be a heartbreaker!
The boy was born in December, with parents Kourtney and Scott Disick waiting a week to announce his name.
Meanwhile, original Kardashian-Jenner mummy Kris also took to social media to gush about her children.
The momager, 59, shared a hilarious photo of little and large daughters Kourtney and Kendall Jenner.
In the snap, model Kendall is towering above her older half-sister in heels.
Kris captioned the snap: "Not sure how this happened but I gave birth to both of them ... #legs #love #familyfun#beautycomesindifferentshapesandsizes #blessed."
All you need to know about Kourtney Kardashian in just one minute:
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