At the beginning of his career, Grass-Mick ran the Phare Littéraire et Artistique, and was in contact with Paul Verlaine, Antoine Bourdelle, Auguste Rodin, Edgar Degas and particularly Henri de Toulouse-Lautrec. He produced drawings for other publications including: the Charivari and the Cri de Paris (a weekly magazine established in around 1896). Between 1897 and 1912 he settled in Montmartre, where he painted local scenes.
From 1902 to 1913 he exhibited at the Salon des Indépendants, the Salon d’Automne and the Salon des Humoristes. From 1912 he lived in Marseilles, where he was partly responsible for rediscovering Puget and the French painter, lithographer and sculptor Honoré Daumier. His lively work captured the Belle Époque artists of the Parisian scene, who were also known through the work of Toulouse-Lautrec; the styles of Toulouse and Grass-Mick are often similar. Simplifying forms and colours, focusing on the essential elements, Grass-Mick portrayed from life both famous people and characters from ordinary backgrounds. He also painted the portraits of Edgar Degas, Henri de Toulouse-Lautrec, Aristide Bruant, Georges Courteline, Jehan Rictus, Jacques Villon, Henri Matisse, Georges Pioch, Éric Satie, Georges Braque, Maurice Utrillo, Suzanne Valadon and Pablo Picasso. In addition to his paintings of scenes from Parisian life, Grass-Mick produced views of Montmartre and sensitive landscapes of Montes and St-Cloud.
