The reality TV star, 44, seemed to miss the star-studded bash as she counts down the days until welcoming her first child with her husband Travis Barker, 47.
Photographs from the star-studded event showed Kim, 43, joined by her sisters Khloe, 38, Kylie Jenner, 26, and Kendall Jenner, 27, as well as her mother Kris Jenner.
However, Kourtney did not feature in the snaps and was seemingly absent from the huge party, which also saw stars including Hailey Bieber attend.
Kourtney also took to her Instagram Stories on Friday to share a cryptic post about ‘walking alone’ amid her ongoing feud with her sister Kim.
She shared a photograph of a drawing, seemingly dated ’97’, showing a girl walking down a long, winding road with the writing ‘walking alone’ scrawled below it.
Earlier in the day, she had also posted a picture of two coffee cups as she enjoyed a morning beverage, with a time stamp of 9.47am on the picture.
She also shared screenshots of herself listening to Fell In Love by her husband Travis’ band Blink-182, from the new album One More Time.
On Friday, Travis – who also appeared to be absent from the party – also took to Instagram to share videos of himself playing the drums as he gave his fans an insight into the recording process for the band’s ninth album.
Heavily pregnant Kourtney is getting ready to welcome a baby boy with Travis. She already shares kids Mason, 13, Penelope, 11, and Reign, eight, with Scott Disick.
MailOnline has contacted Kourtney and Kim’s representatives for comment.
Kim and her sisters Khloe, Kylie and Kendall were all seen at the birthday party together, but have so far remained quiet about the glitzy event on their social media.
Kim officially rung in her birthday on Saturday and cut a glamorous figure as she stepped out on Friday night for her star-studded birthday party.
She put on a busty display in a daring red cut-out dress as she strolled up to the entrance of the swanky restaurant Funke for the glitzy bash.
The mother-of-four was joined at the soiree by her sisters Khloe, Kendall, Kylie and their mother Kris.
It was also attended by the family’s close friend and Kendall’s BFF Hailey Bieber and Kim’s close pal Lauren Sanchez, who is the fiancee of billionaire Jeff Bezos.
Kourtney’s apparent absence from the party comes after she has continued to feud with her sister Kim on their reality TV show, The Kardashians.
Their row began last season when Kim collaborated with Dolce & Gabbana on a nineties themed collection, which Kourtney insisted was copying her wedding theme, which she hosted in Postitano, Italy, months earlier.
And Kourtney was left unimpressed after learning her sisters had a ‘Not Kourtney’ chat to discuss her on the volatile season four premiere of The Kardashians.
During a heated phone conversation, Kim claimed that Kourtney’s close friends had joined her ‘Not Kourtney’ WhatsApp chat to discuss her.
However, Kourtney then shut down Kim’s claims that her own friends were in the group chat as their feud boiled over.
Kourtney took to Instagram to prove her friends are not involved, sharing a screenshot of friends Allie Rizzo Sartiano and Simon Huck saying ‘trolls’ are attacking them for Kim’s claims.
Kourtney later insisted it was just her sisters who are in the chat by responding to a fan’s comment under a post of her baby shower.
‘Are those friends on the ‘not Kourtney group chat’ Cause if so we don’t need them there,’ one fan wrote, to which the Poosh founder responded: ‘No the members of that chat are namely Kim, Khloe, Kendall and Kylie. Case closed.’
To show that her friends had no part in the chat, she shared a screenshot of a text message conversation between her close pals Simon Huck and also Allie Rizzo Sartiano onto her Instagram stories on Friday.
Allie had penned, ‘Should I soft launch the YASS Kourtney group chat?’ with Simon responding with, ‘OMG please! These trolls keep DM’ing me accusing me of being on the other chat.’
The drama kicked off when Kim confronted her sister on the phone about concerns over changes in her personality since her May 2022 marriage to drummer Travis.
‘You’re a different person. We all talk about it,’ Kim told Kourtney, referring to the group that included sisters Khloe, Kendall and Kylie.
‘We’re all confused, and we’re on a group chat that’s actually labeled “Not Kourtney”.’
Kim also claimed Kourtney’s children Mason, Penelope, and Reign had also all ‘come to [her] with problems they have’ about their mom.
The interaction ended with a tearful Kourtney calling Kim an ‘egotistical narcissist’ and telling her, ‘You’re just a witch and I hate you.’
