As expected, the Poosh founder's family showered her in love on social media, with Kim penning a heartfelt note alongside a series of snaps of the pair from when they were younger.
"Happy Birthday @kourtneykardash I had to find some good throwbacks to celebrate you today!," the mum-of-four and wife of Kanye West captioned her Instagram post.
"I remember these moments so vividly. I love your strong will to do whatever makes your soul happy, the love you have for you children and for being the best big sister. I couldn't be more thankful for our memories together. You pack a mean punch I love you so much and can’t wait until this is all over so we can celebrate together."
It's nice to see Kourt and Kim have put their differences aside and moved on from their nasty feud which was shown during last week's episode of Keeping Up With The Kardashians. Fans will remember that their heated argument quickly turned into an all our brawl, with an irate Kim storming out of Khloe's house with dozens of scratches across her back.
"Do you think I want to come into this negative environment with you guys every f*cking day?" Kourt said through tears while screaming at Kim. "Like, it’s torture."
"Just get the f**k out of here. I don't want to even see your f***king face," KKW Beauty founder Kim screamed back.
Moments later, a distressed Kourtney revealed she was sick of filming their long-running reality series, admitting her sisters behave differently towards her when the cameras are rolling.
"It’s your f*cking attitude and your f*cking attitude! Every day," she told them. "When I don’t see you at filming, you’re completely fine when we’re not in this environment. I don’t want to be near your fat ass, OK? I don’t."
And neither was their mother Kris Jenner, who halted production for seven days after watching the worrying clip.
"When my mom saw that, a clip of that, she cried. And was like, 'Who are you guys? Like what is going on?' Kourtney and I are obviously fine now, but we shut down production for a week after that. I think everybody was really shook for a minute, and just was like 'this isn't our type of show, what's happening?' We want everyone to be comfortable and safe."
Kim continued: "It's not my proudest moment, but we were going through it, and she's made the decision to take time off now, and I think she really needs it and I think that will be so much better for her."
The matriarch spoke out about their physical fight after the first trailer for the latest season dropped in February, confirming she was mortified and disappointed when she watched the footage.
“I wasn’t there when they had that argument. And I have not seen them really fight like that since they were in high school,” the 64-year-old said.
“There was one time, I think it was way back when, when Kim … did anybody see when Kim beat one of the kids over the head with her purse because her rims on her car weren’t right, it was so silly. It took me back to that, but it made me really sad. I was like ‘You guys can’t be fighting with each other,'" she added. “That’s ridiculous, you know. Grow up."