Decked out in a skintight, short, boob-revealing black dress ... the 44-year-old hit Hailey Baldwin's PrettyLittleThing launch party Monday night at Catch in West Hollywood.

As we previously reported, Larsa has called it quits with her longtime NBA husband, Scottie Pippen, after 21 years of marriage ... but both sides insist it's a peaceful split.

Our sources tell us ... both sides recognized the marriage wasn't working anymore and Larsa felt it was best to divorce so she can be open to meeting new people.

Larsa hasn't exactly been hiding out in her basement since the breakup -- she turnt up at Kendall Jenner's Halloween party last week in a super sexy costume.

The message here is clear ... Larsa's ready for her new chapter -- bombshell bachelorette.