Early in life, Courtois revealed an interest in art and entered the École municipale de dessin in Vesoul (Franche-Comté).

Courtois was in close friendship with fellow student Pascal Dagnan-Bouveret, with whom he maintained a fashionable studio in Neuilly-sur-Seine from the 1880s.

He was awarded a gold medal at the Exposition Universelle in 1889 and exhibited at the Salon de la Société Nationale des Beaux-Arts from 1911 to 1914.

[citation needed] Among his students were Willard Dryden Paddock, Mary Rose Hill Burton, and Sara Page.

They lived in the same studio building in Paris, socialized daily, shared many artistic ideals and supported each other in their work.