
Three hundred people attended, including rapper Lil Wayne, comedienne Kathy Griffin, and sister Nicky, at a 1920s-themed party in the Hollywood Hills.
Prior to the event she tweeted, "Getting ready for my big birthday bash tonight! So excited! Yay! :)"
The reality TV star officially passes the milestone on Thursday, but she began celebrating two days early when Waits surprised her with a bright yellow Lexus, a day after the pair enjoyed a romantic Valentine's Day meal together.
Hilton was photographed hugging and kissing Waits after the sports car was delivered to her driveway.
