An autodidact and son of the French rural working class, Chaissac became involved in the art world when he lived next door to Otto Freundlich and Jeanne Kosnick-Kloss in Paris during the 1930s. They showed him modern art and supported his efforts to paint, helping him along and promoting his work. Gaston Chaissac is often considered to be part of the Art Brut or Outsider Art category. Some artists have described his style as "modern rustic". Chaissac’s art was praised by Jean Dubuffet when he first came across it in 1946.