In the sweet picture, which was uploaded on Wednesday, the Keeping Up with the Kardashians star posted a picture of Psalm in a small play area.
The youngster looked like a young bear cub, dressed from neck to toe in some cute brown clothing.
Watch: Kim Kardashian shares the sweetest video of youngest child, Psalm
"The sweetest boy!" the loving parent wrote. "You can't tell here but he has the most infectious smile! I love you baby Psalm."
The adorable picture of the tot had Kim's fans all cooing the same thing about the young child.
"Cutest little guy!" wrote PR executive Simon Huck, while another fan wrote: "Adorable Psalm!" Many other fans continued to write how Psalm was "cute" or a "cutie pie."
One poked fun at Kim's caption, jesting: "Can we see the smile…what a cliffhanger LOL."
Another commented on how quick the youngster was growing up, saying: "He got so big fast, wow!"
Fans were all saying how adorable Psalm is
TMZ reported that Kim filed for divorce on Friday, and that she filed for joint legal custody of the couple's four children.
It was reported in January that the couple had decided to call it quits, with numerous media outlets reporting that they were set to divorce despite efforts to salvage their relationship.
The famous couple's former neighbour, Kathy Griffin, seemingly confirmed the news in January, tweeting: "I think she really tried. Truly loves him. I like her. He certainly isn't the devil or anything, but I believe she tried everything to make it work.
"He made her laugh a lot and she embraced his eccentricities. She loves being a mom more than anything. There's my two cents."
Kim and Kanye have four children together
Kim and Kanye married in Italy in May 2014 after they had already welcomed their eldest daughter, North.
This will be Kim's third divorce. She was married to music producer Damon Thomas from 2000 to 2004. She then wed Kris Humphries in August 2011 but filed for divorce after just 72 days. This is Kanye's first divorce.
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