Dullin was a student of Jacques Copeau. He was also a major theater teacher, who trained a whole generation of French actors. Before Copeau returned to Paris in June 1920, Charles Dullin had already taken on students and was giving acting lessons at the Théâtre Antoine under the tutelage of Firmin Gémier, the actor who originated the role of Ubu in Alfred Jarry's Ubu roi. The small of group of students, among them Antonin Artaud, developed into the "Atelier", Dullin's workshop for young actors that would prove to have a lasting effect. With this small group of actors he eventually settled in the Théâtre Montmartre, renamed the Théâtre de l'Atelier where he would remain until the beginning of World War II.
In the tradition of Copeau, Dullin preached and practiced respect for the text, a simplified stage décor and favored a poetic rather than a spectacular perspective on the mise-en-scène, placing the actor at the center of the theatrical endeavor. Dullin also played many roles on the screen, especially when he needed money to continue to support his theater. He was one of the major French actors both on the stage and the screen during the 1930s.