The Fight club actor hosted an event in New Orleans, Louisiana on Saturday (17May14) to raise money for his Make It Right Foundation, which aims to build environmentally friendly housing in parts of the city left ruined by Hurricane Katrina in 2005.
A video has emerged of Pitt taking to the stage during Mars' set and picking up a tambourine. He dances and shakes the instrument during a cover of James Brown classic Get Up (I Feel Like Being a) Sex MAChine.
Later that evening, the actor was joined by Sandra Bullock to host a live charity auction, which reportedly brought in more than $4 million (£2.5 million). Other celebrities in attendance included Pitt's fiancee Angelina Jolie, Modern Family actress Sofia Vergara and comedian Chris Rock.