The 39-year-old star also shared several snaps of her children playing together at the party, including one video that showed the birthday boy wearing a festive dinosaur mask.
In the video, Kardashian was seen calling out Chicago who was scared and began to move away. "Look at Saint as the dinosaur, Don't be scared. It's just your brother with a mask," she said.
Prior to the big party, Kardashian documented the set-up of the bright, candy-colored birthday cake, in a series of videos on Instagram as a glance of the extravagant party. The mother of four said, "Look, guys! Saint's dinosaur party is today, How cute is everything? We are still setting up."
In the themed party, the treats were decorated with little dinosaur claws or eggs, and guests could stop to get 'Raptor Juice' after walking through the 'dinosaur cave.' There was also a dinosaur ball pit for children to play in as well as multiple DIY craft stations, 'Jurassic Jewellery' stop, and also included 'Dino Domes, 'where children could make their own dinosaur habitats.
Kardashian West also explained that the party also had a large dig site "where we are all going to hunt for fossils, and you have to put on all your gear,"
She said to Saint, "I bet we're gonna have fun," who pointed out a fossil he had found.
On Thursday, the proud mother shared a sweet tribute to her second eldest son on Instagram in honor of his birthday where she gushed in the heartfelt post. She praised her second-oldest child, "I have no words to describe how much I love your smile and those curls of yours Saint! You bring so much joy into my soul. You are so kind, loving and just so thoughtful and sweet! I am so happy today if your 4th birthday and We get to celebrate how much you've grown!"
Kardashian West added, concluding with an adorable note "Happy birthday my sweet sweet Sainty, When I say to him my sweet sweet Sainty, he says back to me my sweet sweet sweet sweet Momma, the best momma in the world and the only momma I ever want! HOW CAN YOU NOT MELT AT HIS SWEETNESS)."