His father, Almazor Gauthier, sang Sundays in the Catholic Mass and his mother, Antonia Bélisle, played piano.
Encouraged to take part in a contest for singer-songwriters put on by CKVL, in Montreal, in 1959, he won first prize for "Le Soleil brillera demain" ("the sun will shine tomorrow").
Gauthier's success reached into France as well, and in 1966 he performed in Paris at the Olympia with Gilles Vigneault, Pauline Julien, and Clémence DesRochers.
He was the male lead in and wrote music for the film Entre la mer et l'eau douce (1967), which was directed by Michel Brault and starred Geneviève Bujold.
[4] The other films he acted in during this period were: Partis pour la gloire (1975) directed by Clément Perron for which Gauthier also composed the theme song "Les Beaux Instants", which appears on the LP of that name (1975, Presqu'Île PE 7500).
He appeared in Gilles Carle's La guêpe (1986), François Labonté's Henri (1986),[5] Louise Carré's Qui a tiré sur nos histoires d'amour (1986), Yves Dion's Les Enfants de la rue (1987), Michel Brault's short drama L'Emprise(1988) (once again with Geneviève Bujold), and Robert Ménard's L'Homme de rêve (1991).
In the following years he put out four CDs: L'Agenda (1993, Transit TRCD-9105), Quebec-Love (a compilation, 1994, Gamma GCD-504), Au Temps Des Boîtes à Chansons (recordings made in 1962, and reissued in 1998), and Jardins (1998 — GSI Musique GSIC-989).
In 1999, Gauthier appeared in the critically acclaimed film by Michel Brault, Quand je serai parti... vous vivrez encore (English title: The Long Winter).
In November 2000 Gauthier received the Prix Hommage of the SOCAN (Society of Composers, Authors and Music Publishers of Canada) for a lifetime of creativity.
Following that album a concert performance by the same name (L'homme qui passait par là) was presented at the Corona Theatre in Montreal and also at the Cabaret du Capitole in Quebec City in March 2002.
This performance included a string quartet, and host of projections from film archives as well as exceptional dramatic lighting; it underscored Gauthier's 40-year career.
Starting in 2003 a series of retrospective recordings came out, Le plus beau voyage de mes chansons 1959–1972 (GSI Musique GSIC-905) in which Gauthier reinterpreted his previous hits with a new group of musicians.
And along with Daniel Boucher, Gauthier appeared in another homage to Félix Leclerc at the Fête nationale du Québec, 2003, at the Parc Maisonneuve, Montreal.