The reality TV star, 34, looked ready to party the night away in a form-fitting black jumpsuit with a plunging neckline. She jazzed up her dark ensemble with gold studded earrings, matching thick bangles and a rectangular, lucite clutch. Kourtney wore her brunette locks down, styled to one side.
The mother-of-two, who is in a long-term relationship with the father of her children Scott Disick, was clearly enjoying her night off with her "squad".
Kourtney took to Twitter to document the girls' celebrations in Sin City. The friends prepared for their night out with a luxury spa session and took group photos relaxing in robes and sipping champagne.
"Squad ready. #viva #las #vegas," wrote Kourtney, alongside a photo of the girls dressed in black and ready to take on the night.
The group then headed out to the club by limo and continued snapping away. "70s limo ride," she tweeted, followed by "Vegas get ready" and "Up in tha club!"
Earlier in the day Kourtney made a special appearance at her family's celebrity boutique shop, Kardashian Khaos. The eldest of the Kardashian sisters once again turned heads in a glitzy gold mini dress that was bejewelled with different coloured gemstones.
Meanwhile, her three-year-old son Mason and thirteen-month-old daughter Penelope were in safe hands with their grandmother Kris Jenner in Malibu.