Comeau started his music career in Reset with bandmate Pierre Bouvier. After the band's first CD was released, Comeau left the band and went to McGill University to pursue a degree in law.
After reuniting with Bouvier at a Sugar Ray concert, he soon left school and helped Bouvier to form Simple Plan. In Simple Plan, Comeau, along with Bouvier, are the main songwriters. He is sometimes known as the "writer" of the band as he does most of the lyrics, writes all the concepts, and writes the scripts to Simple Plan's music videos.