The mother of three gave the birthday boy a special shout-out on Instagram Thursday writing, “Happy birthday baby daddy!”
Along with the caption, Kardashian, 37, posted a photo of the pair when they were still dating. The parents of Mason, 6, Penelope, 3, and Reign, 1, split in July 2015.
A source tells PEOPLE that Kourtney celebrated with Scott at Nobu in Malibu on Thursday night along with other members of the KarJenner crew.
Disick, who will be celebrating his birthday at 1Oak in Las Vegas on Friday, was in good spirits ahead of his big day.
“He seems like he’s in a really good place,” a source told PEOPLE. “He’s single for the first time in a long time, so of course he’s having fun. He’s going out and talking to people, but he also loves his kids and is making them a priority. He’s pretty upbeat and seems content with life.”
“Happy Birthday Scott!!” the momager’s message read. “Thank you for being a loving and devoted father to my beautiful grandkids. I am so blessed to be able to call you my son. I love you and hope you have the most amazing day!”
While Khloé wrote, “Happy birthday lord!!! We’ve been through it all and I wouldn’t have it any other way! Forever my brother and forever my bestie! Love you @letthelordbewithyou.”
Kardashian, 29, called Disick his “brother for life” in his shout-out. “HAPPY BIRTHDAY TO MY BROTHER FOR LIFE @letthelordbewithyou ! He is such an amazing Father to 3 Beautiful children and I Love this man very much!! You are very Blessed and this year WILL be a great one for you once again! LOVE YOU, Bob.”