Kim also shared a selfie photo and video of her and Paris.
The heiress, socialite and former reality star had actually turned 38 in February.
"Happy birthday Paris, even though your birthday was month ago," Kim says to Paris in another video. "But she deserves it."
The two have known each other since they were children and appeared to be close in the early 2000s, and Kim famously helped Paris rearrange her closet on the latter's reality show The Simple Life. The two then feuded several years later, then eventually became friends again.
In 2016, the two reunited at Kris Jenner's annual Christmas Eve party. Paris also attended the family's most recent holiday bash, this time held at Kim and husband Kanye West's home.
Watch Keeping Up With the Kardashians when it returns for a new season on Sunday, March 31 at 9/8c only on E!