Born in North Bay, Ontario, Gauthier moved to Toronto after living in Washington State and Hamilton. He studied under Group of Seven artists Franklin Carmichael and J.E.H. MacDonald, and later worked as a commercial artist for Sampson Matthews Limited for 37 years. At age 35, art director A.H. Robson recognized Gauthier's potential, praising his originality and skill. Gauthier frequently accompanied A.J. Casson on sketching trips and exhibited with the Group of Seven. In 1947, Gauthier was elected an Associate of the Royal Canadian Academy and was a member of both the Canadian Society of Painters in Water Colour (1931) and the Ontario Society of Artists (1933). His works are part of the National Gallery of Canada’s collection, and he is also known for his portraits of Tom Thomson, the Group of Seven, and their contemporaries, commissioned by the McMichael Canadian Art Collection.