The daredevil performed a rendition of Lil Wayne's Runnin' at the event in West Chester, Pennsylvania on Saturday (23Jul11), which was held in memory of his friend who died in a high-speed car crash last month (Jun11), alongside Margera's Jackass co-star Ryan Dunn.
The fundraiser was held by two bands, The Moxy and Backwoods Payback - who were pals of both Dunn and Hartwell - in a bid to raise funds for Hartwell's widow, Rachel.
Moxy bassist Ahmed Smith tells the West Chester Daily Local News, "Tonight's pretty much about taking a bunch of Ryan and Zach's friends and getting together and having a good time. We basically just took a house party and put it into a show."
Dunn and Hartwell were killed when the Jackass star lost control of his Porsche while travelling at more than 130 miles per hour (209 kilometres per hour) near West Chester. Officials subsequently revealed Dunn had been drinking with friends before the accident and was intoxicated when he got behind the wheel.
The TV stuntman was killed in a horrific high-speed car crash in the early hours of Monday morning (20Jun11) when his Porsche spun out of control and smashed into trees in West Goshen Township, Pennsylvania.
Dunn died along with his passenger, Jackass production assistant Zachary Hartwell, and a toxicology report allegedly suggests the star was over the drink-drive limit.
A private remembrance service for Dunn was held at a funeral home in West Chester, Pennsylvania on Wednesday and his pals Knoxville and Margera were both among the mourners.
A full funeral will be held later this week (beg20Jun11), but the service has been threatened by members of the controversial Westboro Baptist Church, who have vowed to picket the memorial.
Funeral director Joseph DellaVecchia, who is in charge of the service, is aware of the church's plans, but reveals police officers will be on hand to make sure there isn't any trouble, telling CNN, "We can't stop someone from coming to a public funeral, but this is private, and the police have everything under control."