The mother-of-two looked stunning in her black jumpsuit with a plunging neckline at the Labor Day Bash at the Hyde Bellagio inside the Bellagio Hotel and Casino on Saturday night (31 August).
Kourtney's long-time boyfriend Scott Disick didn't appear to be with her, instead the glam star spent the night partying with her "squad" of good friends.
Tweeting a photograph of the group together early in the evening, she added the caption: "Squad ready. #viva #las #vegas."
Earlier in the day, the yummy mummy hosted a meet and greet with fans at the Kardashian Khaos store at the Mirage, looking lovely in a bejewelled dress and hot pink heels.
Kourtney's sisters Khloe and Kim were not in Vegas over the weekend, although that's perhaps unsurprising.
Khloe has been keeping a low profile following US reports that she's going through a rocky patch with husband Lamar Odom. She hasn't commented and has been seen out and about wearing her wedding ring in recent days.
Last week, the couple hit the headlines again for another reason: Lamar was arrested on suspicion of DUI and had his driving license suspended for a year because he allegedly failed to submit to a chemical test.
Kim, meanwhile, has rarely been seen since giving birth to daughter North West - her first child with rapper boyfriend Kanye West - on 15 June.
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