Rousseau's portraits and landscapes often had a childlike or naïve quality. Since he had not learned anatomy or perspective; their vivid colours, ambiguous spaces, non-realistic scale and dramatic intensity gave them a surreal quality. Sometimes Rousseau borrowed details from paintings he had viewed at museums or images he had seen in books and magazines, transforming them into elements of his own visions.

His earliest known works were local views, naïve in both their detail and in their perception. This seemingly direct story telling then led to inventive, imaginative, and dream-like works. However obsessed Rousseau was with exact and particular detail, he was able to control his composition, consolidating what might have been a host of minute and disparate observations into a coherent whole. He worked slowly and carefully, applying many layers of paint and exotic jewel-like colour.

In 1884 Rousseau had begun to copy work in the Louvre. He studied briefly with the academic painter Jean Léon Gérôme at the École des Beaux-Arts. In 1886 Rousseau exhibited for the first time at the Salon des Indépendants, where he showed fairly regularly until his death. He supported himself by giving lessons in painting, diction, and music and he was a skilled violinist.