The pre-bday festivities -- Woods turned 27 on Sept. 23 -- went down on Sunday in Malibu, CA ... where Jordyn was all dolled up in a cream-fitted dress for her big day.

The model and socialite's private event had several celebs in attendance, including Angel Reese, Taina Williams, and Jena Frumes.

But, of course, the biggest star (literally) was her NBA star boyfriend, KAT ... and the two lovebirds danced the night away.

At one point, Karl ran up behind Woods after she blew out the candles on the birthday cake ... and started twerkin' on her 7-foot tall baller boyfriend while everyone cheered 'em on.

"Happy Birthday to my world @jordynwoods," the 28-year-old hooper wrote in a bday post on social media.

Woods and KAT -- who signed a $224 million contract extension with the Timberwolves a few years back -- have been very public about their relationship ... which started in 2020, with the couple sharing their travel adventures and extravagant gift-giving.

In fact, for KAT's birthday last year, Woods gifted him a gigantic diamond ring with over 15 carats of near-flawless diamonds.