But the mum of three was left partying without sisters Khloe and Kim Kardashian for her big night, in LA.
The brunette beauty looked incredible as she celebrated her new venture, at hotspot Poppy.
She opted for a black sequinned mini-dress, from her own collection, along with a pair of strappy heels.
The Keeping Up With The Kardashians star scraped her long locks into a high ponytail and a toned-down make-up look.
She was joined by sister Kendall Jenner for the night, who dressed down for the occasion in jeans and a baggy grey top.
But Khloe, who is rumoured to be pregnant with her first child, and Kim – who recently confirmed she will be welcoming a third baby with husband Kanye West, did not attend the bash.
Kourtney Kardashian’s new PrettyLittleThing collection is now available [PrettyLittleThing]
Kylie Jenner, who has also faced heavy speculation she is expecting a baby with Travis Scott, and mum Kris were also no-shows.
But Kourtney didn’t seem too bothered, as boyfriend Younes Bendjima stayed by her side the whole night.
The 38 year old recently made headlines after it was claimed she has banned ex Scott Disick’s new girlfriend, Sofia Richie, from seeing their kids.
According to reports, the reality star – who shares children Mason, Penelope and Reign with the businessman – wants to protect her little ones.
“Kourtney is a fierce mum, and she’ll do whatever it takes to protect her kids,” an insider reportedly told The Sun Online.
“She doesn’t want them getting confused by Scott’s new girlfriend – Mason is seven, old enough to understand a lot of things now, and Kourtney doesn’t want them meeting another one of Scott’s new girlfriends, only for her to disappear from their lives in a month.
“Plus, it would kill her to see another woman ‘playing mum’ to her kids in public. It would break her heart.”
OK! Online has contacted reps for Kris, Kim and Khloe for a comment.