Brad Pitt seems to be getting his groove back.

As his contentious divorce and custody battle with Angelina Jolie rages on, the slimmed down actor made a rare party appearance, showing up at the fourth annual charity ROCK4EB! event, an intimate benefit held at a private home in Malibu on Jan. 14.

Brad was there to introduce his old rock star buddy Chris Cornell, who performed at the benefit along with Sting.

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According to E! News, the two musicians delivered acoustic renditions of Sting's old band The Police's 1983 hit "Every Breath You Take" plus Chris' old group Soundgarden's 1994 hit "Black Hole Sun."

"[Brad] was in a great mood," a source told E! "He hung out with his peeps."

Chris enjoyed seeing his old friend too. "Had an amazing night performing for #RockforEB with @theofficialsting & #bradpitt," the one-time grunge rocker captioned a snapshot of himself with the guys.

Had an amazing night performing for #Rock4EB with @theofficialsting & #bradpitt

A post shared by Chris Cornell (@chriscornellofficial) on

Other stars at the benefit -- which was sponsored by jeweler Alex and Ani and benefited the Epidermolysis Bullosa Medical Research Foundation, which is dedicated to battling the skin disease, a rare genetic connective tissue disorder for which there is no treatment or cure -- included host Zach Galifianakis, Courteney Cox, Heidi Klum, Trudie Syler, Kaley Cuoco, Garrett Hedlund, Cindy Crawford and husband Rande Gerber, Elizabeth Olsen, Scott Foley and wife Marika Dominczyk, Aaron Taylor-Johnson and wife Sam Taylor Johnson, Ed O'Neill, Charlie Hunnam, Rami Malek and more.

One elated fan snapped a selfie with Brad -- who is on the charity's board of directors -- captioning it, "best day ever. #rock4eb."

best day ever. brad freaking pitt. #rock4eb

A post shared by rebel scum ✊🏽 (@kallista.a) on

Another attendee shared a video of Brad introducing Chris, whom he described as "a very, very good friend of mine."

#RockforEB #bradpitt #chriscornell #sting

A post shared by Vaitiare Hirshon (@vaitiarehirshon) on

Brad's appearance came just five days after he and Angelina issued a joint statement -- their first since they broke up -- revealing they'd finally reached an agreement to keep their divorce and custody issues in a private forum and that they would be turning to a private judge for help.

"The parents are committed to act as a united front to effectuate recovery and reunification," they said in their statement.