Lefebvre was a founding member of the Orphéon de Montréal and gave concerts in Canada and the USA. His repertoire included the roles of Joseph in L'Enfance du Christ, Vitellius in Massenet's Hérodiade, and the High Priest in Samson et Dalila. In 1923 he sang the role of Antipas in the premiere of Guillaume Couture'sJean le Précurseur, and two years later he sang the Pharisee and Zacharias in the same oratorio. He also sang for radio stations CKAC and CFCF, and on the CBC. His wife Maria (née Verner), a pianist, frequently accompanied him in his recitals. Lefebvre was a teacher at the Schola cantorum in 1922 and also taught privately.
His son Germain (born Montreal 10 Jan 1924, died 3 Dec 2008) studied Gregorian chant with Clément Morin 1936-42 and later worked with Salvator Issaurel 1942-4 and then for 10 years with Pauline Donalda. Germain succeeded his father as choirmaster at St-Jean-Baptiste Church 1946-67 and worked in the same capacity at St-Sylvain de Laval, Que, 1967-77. He sang for CBC radio and TV. He was a teacher 1960-72 and a teaching consultant thereafter for the Chomedey-Laval school board 1972-87 and set up several school choirs and instrumental ensembles. He was the founding director (1968) of the Choeur de Laval, whose 1979 recording of Dubois' Sept Paroles du Christ was issued on SNE 504.