He studied singing in Montréal and won a Prix d'Europe in 1926 to continue his studies in Paris. Subsequently he became principal baritone at the Opera of Algiers. Returning to Canada in 1930, he performed with the Bytown Troubadours and over the next five years performed regularly with the Société Canadienne d'opérette. Meanwhile, he was composing songs that he began to perform in concerts and radio broadcasts, and later record with the Trio lyrique (Anna Malenfant, Ludovic Huot). With Charles Goulet he founded in 1936 the Variétés lyriques. Subsequently he directed many of their productions at the Monument National in Montréal.
By the early 1940s he was most renowned for his songs, of which he eventually wrote over 100 plus choral pieces and harmonizations of folk songs. "Chanson du maître cordonnier" and "Aglae" became well known in Québec and France. His lyrical chansons are tinged with elements of folk song in their use of language and sound. Often he used refrains in the structure of the litanies of the Roman Catholic Church to underline a humorous bent. Some of his songs have been republished in Songs III to French Texts, volume 12, and portions of his Messe en Do in volume 20 of the Canadian Musical Heritage Society series. In the 1950s and 1960s Daunais directed many operettas for CBC-TV and for Place des Arts. He received many honours, including the Pix de Musique Calixa-Lavallée (1977), Officer of the Order of Canada (1978) and is an inductee of the Canadian Songwriters Hall of Fame.