Credit: Jeff Bottari/Getty Images

All eyes were on Katy Perry when she hit the red carpet Friday night.

In her first official appearance since Russell Brand filed for divorce December 30, the 27-year-old singer joined her friend, jewelry designer Markus Molinari, and David Arquette on behalf of GiveLove at 1Oak in Las Vegas.

"I told her about the cause and she wanted to support it," Molinari told Us Weekly of Perry. "We support each other and that's what friends do."

Sporting a bright blue bob, Perry showed off her fit figure in a body-hugging LBD by McQ. "She was very bubbly and happy looking," an onlooker told Us. Indeed. When asked if she was having a good time, "The One That Got Away" singer told Us: "Yeah!"

Proceeds from the event benefit GiveLove's efforts "to provide temporary housing solutions and sanitation systems in earthquake-stricken Haiti." Other stars who turned out for the event include 90210's Shenae Grimes, Paris Hilton, Mehcad Brooks and DJ Mia Moretti.

It's been a tough month for Perry, whose ex Brand, 36, has been trashing her to his conquests. "He's spoken terribly about Katy to them," a source told Us of Brand, who's already found one particular woman to "explore a relationship" with. "[Russell] told her he wanted her to move in with him after the divorce is final."