Taking to Instagram, Khloe shared a sweet message for her beau and even posted a picture of the couple at Tristan's party.
"To the happiest of birthdays my love! To the first of many more together! May God continue to bless you in all of your days! And may we forever look at one another like this," she wrote alongside the snap.
It comes after Khloe revealed that she was "in love" with Tristan.
"At this moment, a few days into 2017, I feel incredibly clear and probably the happiest I've been in years. It's such a great feeling that I have my happy back!