André Lortie's first singing teacher was Roger Larivière. He later studied at the CMM and in New York. In 1952 he made his debut with the Variétés lyriques as Alexius in Oscar Straus' The Chocolate Soldier. For the Montreal Festivals he sang the role of Porcus in Jeanne d'Arc au bûcher (1953), Basilio in The Marriage of Figaro (1956), and Torquemada in L'Heure espagnole (1961). With the Opera Guild he portrayed Spoletta in Tosca (1957), Caius in Falstaff (1958), Remendado in Carmen (1960), Gastone in La Traviata (1962), Goro in Madama Butterfly (1965, 1969), Benoit in La Bohème (1966), and Basilio in The Marriage of Figaro (1967).
A grant from the Quebec government enabled him to work in 1960 with the American Opera Society in Philadelphia, Washington, Baltimore, and New York; he took the part of Lacouf in Poulenc's Les Mamelles de Tirésias in its US premiere at Carnegie Hall. During the World Festival (Expo 67) he performed with the MSO, the COC, and the Théâtre lyrique de Nouvelle-France. The same year he participated in the premiere of Somers'Louis Riel (the roles of Ambroise Lépine and Père André) in Toronto, and repeated the roles in Montreal and on CBC TV.
He sang at the NAC in The Marriage of Figaro in 1971 and 1972 and La Belle Hélène (Ajax II) in 1973 and 1975. With the Opéra du Québec he sang the roles of Roderigo in Otello in 1973, Bardolfo in Falstaff and Goro in Madama Butterfly the following year and Benoit in La Bohème in 1975. In 1973 he also sang in Edmonton and Vancouver in Tosca and at Hartford, Conn, in Carmen. With the Opéra de Montréal, he sang in Tosca in 1980, in Madama Butterfly in 1981 and 1988, and in Werther in 1982. He was Spalanzani in The Tales of Hoffmann with the COC in 1981. He also sang the roles of Schmidt in Werther and Spoletta in Tosca at the Kennedy Center in Washington, DC, and Pang in Turandot with the Calgary Opera.