The Canadian Encyclopedia states, "Considered too avant-garde for his time because of Debussy's influence on his music, Mathieu gained recognition too late to inspire the generation that followed."
The pianist Léo-Pol Morin was one of the few important exponents of his work, notably including Mathieu's Chevauchée and Trois Préludes in his concert repertoire.
In 1929 he founded the Canadian Institute of Music, an organization whose aim was to enable "young artists and literary talents to perform before an elite audience".
He also taught André Mathieu, the son of his marriage to the violinist Mimi Gagnon, who had a highly successful career as a concert pianist.
[1] In 1955 Mathieu joined the faculty of the Conservatoire de musique du Québec à Montréal where he taught music analysis through 1959.
He was named an associate of the Canadian Music Centre posthumously and many of his papers and manuscripts are part of the collection at the Library and Archives Canada.