Mitchell was a central figure in Prism and was one of its longest serving members. He was originally a member of the Vancouver band, Seeds of Time, as guitarist in the late 60s and early 70s. He left to front another Vancouver band, Sunshyne. He was recruited to transform their sound from jazz-rock into blues rock in an effort to land a recording contract. Mitchell wrote the songs "I Ain't Lookin' Anymore" and "Don't Let Me Find Out" for the original demos. Bandmate turned producer Bruce Fairbairn also used songs by another Sunshyne member, Jim Vallance, to secure a record deal for the band. Mitchell voluntarily withdrew as lead vocalist and was replaced by Ron Tabak during the recording of the demos. The band was renamed Prism and the self-titled debut album released in 1977. Only Mitchell's "I Ain't Lookin' Anymore" was included while Vallance had 7 compositions. The album hit platinum status in sales, a first for a debut artist in Canada. Although Vallance was initially the principal songwriter for the band, Mitchell assumed the role after Vallance quit in 1978. Mitchell composed "Armageddon", the title track for the third album and one of the band's most recognizable songs. He received a SOCAN Song of the Year award for "Night to Remember", a ballad he also wrote for the Armageddon album. Mitchell first left Prism mid-tour in 1982. He reunited with his former bandmates in 1988. In 1993 Prism released Jericho, an album with Mitchell writing several of the songs.
Mitchell is a graduate of the University of British Columbia and holds a Masters in Adult Education. He has served as the Ombudsman of the Alma Mater Society.
Mitchell published a study of student-teacher practice in 2002 under the title of "Whiney Student Teachers."
He lives and works in Vancouver and is a regular performer in the Vancouver blues scene.