Jamieson is best known as the front man of alternative rock band Grinspoon. In July 1995, Jamieson, on lead vocals and guitar, formed the group with Pat Davern on lead guitar, Joe Hansen on bass guitar, and Kristian Hopes on drums. Their debut gig was at a Lismore hotel, The Gollan. Greg Lawrence of WHAMMO website described Lismore's late 1980s music scene as a "collection of manic and unpredictable bands that played the - even more - unpredictable venues at the time". He opined that it was no surprise that Grinspoon were "a young troop of riff-masters balancing on the thin line between hard and punk rock". He praised the "strengths of the band" including Jamieson's "casual charisma".