In a promotional interview streamed from the Rancid website before the release of Rancid (2000), he revealed that his style was heavily influenced at an early age by John Entwistle, bassist for The Who. He typically uses a hard pick but sometimes will fingerpick.
Freeman's playing style is considered atypical in the punk rock world due to his frequent use of scales and arpeggios as opposed to "motoring" through a chord progression's root notes as is typical of punk bass playing. Freeman's solos in the songs "Maxwell Murder", "White Knuckle Ride", and "Axiom" are among his most lauded.[by whom?]
Although Armstrong and Frederiksen are the principal singers in Rancid, Freeman has taken the lead vocal duties in a number of gritty sounding songs through the years, including the songs "Black and Blue", "Rigged on a Fix", "Black Derby Jacket", "Tenderloin" and, "L.A. River". He is known for possessing a deep and raspy singing voice. Freeman was also the co-lead vocal for the first Rancid album, before Frederiksen joined the band.
In May 1987, Freeman and Armstrong formed the band Operation Ivy. After Operation Ivy broke up in May 1989, they formed a new band, Downfall, which included all but one member of Operation Ivy and two additional members. Downfall recorded a 10-song album which has never been released, then broke up. Freeman and Armstrong next formed Generator, who played a number of shows, but are not known to have recorded anything. After that, Freeman played with the political punk band MDC for about a year.
After Operation Ivy, Freeman and Armstrong formed the ska band the Dance Hall Crashers, however they left the band shortly after its formation. The band went on to become moderately successful throughout the 90s.
He joined MDC in 1990, completing one US and one European tour and playing bass on their 1991 release Millions Of Dead Cops II: Hey Cop! If I Had A Face Like Yours.... The lineup for this version of the band consisted of Freeman, original singer Dave Dictor, original drummer Al Schvitz and guitarist Bill Collins, formerly of Fang, Special Forces and Intensified Chaos.
He joined The Gr'ups in 1991. In 1992, Freeman and Armstrong recruited drummer Brett Reed and formed Rancid. Rancid is his most successful band yet. He considered Rancid a side project until Armstrong had proved to him that he had his alcoholism under control. Guitarist Lars Frederiksen joined the band later in 1993. Their partnership has continued with Freeman contributing basslines to selected tracks by the Transplants, one of Armstrong's side projects.
Following his departure from Social Distortion, Freeman was diagnosed with lung cancer in May 2005, but was dismissed as abnormal tissue growth and not terminal to his health in June 2005. He had been a smoker for 20 years but had quit, seemingly by coincidence, shortly prior to this. He learned to play the mandolin so he would have something to do with his hands as heard on the Lars Frederiksen and the Bastards album, Viking.