The pop star had a small bash at Coco De Ville, a colorful West Hollywood hot spot inside the STK restaurant, a source inside the club confirmed to Access.
Rihanna turned 21 on February 20, but a 200-person event in NYC to celebrate her big day was canceled in the wake of her alleged beating at the hands of boyfriend Chris Brown on February 8.
The singer's soiree on Tuesday appeared to be just a small gathering with friends, including Brody Jenner's pal, Frankie Delgado.
However, despite their reported recent reconciliation, Chris Brown was not present at the event, the source added.
Rihanna and her group hung out on the club's private patio where she and enjoyed a pink cupcake tower, which featured a flower sparkler that bloomed when it was lit, according to the source.
The pop star kept her sunglasses on all night, according to the source.
Last week, Brown was charged with two felonies over his alleged beating of Rihanna – assault and making criminal threats. However, his arraignment was postponed until April 6, when the singer is expected to enter a plea on the charges.
As previously reported on AccessHollywood.com, Brown and Rihanna resumed their relationship weeks after the February 8 incident. They stayed at Sean "Diddy" Combs Star Island, Miami Beach mansion and most recently were recording new music in a Los Angeles studio together. The music recording sessions are expected to carry on through this week.
Related Content from AccessHollywood.com:
PLAY IT NOW: Rosie O'Donnell Sounds Off On Chris Brown & Rihanna
PLAY IT NOW: Chris Brown Charged With Two Felonies (March 5, 2009)