In 1904 Zak had returned to Paris, where he settled for the next decade. This year he also debuted at the Salone d’Automne with Etude. Two years later he became a member of that Salone, sitting on the jury of drawing section. He also exhibited at the Salon des Indépendants. In 1907 Zak was invited to participate in exhibitions of the "Sztuka" Polish Artists Society and in 1909 he befriended members of the "Rytm", i.e. Tymon Niesiolowski, Roman Kramsztyk, Mela Muter, Tadeusz Makowski. Because of the fact that the vast number of Poles had gathered around him, Zak became one of the founding members of the Polish Artists Society in Paris. In 1911 Zak had his first one-man exhibition at Galerie Druet in Paris and a year later, after Museé de Luxemburg had bought his painting "Woman’s Head", Zak was officially recognized in France. In 1913 he took a part in the Armory Show, the exhibition which took place in New York, Detroit and Chicago. Both of his canvases where sold to private collectors. Between 1916 and 1923 he lived in Poland, but after that he decided to come back to Paris. These were prosperous times of his work, social life and also finances. Among others, he had a few solo exhibitions in Parisian galleries. Zak died suddenly of a heart attack in 1926.

In one of the contemporary collection’s room in Art Institute of Chicago hangs "Shepherd" painted between 1910 and 1911 by Zak. This canvas was bought at the New York leg of the famous Armory Show in 1913 by Arthur Jerome Eddy. Artur Tanikowski, the author of "Eugeniusz Zak" says the painting was inspired by Pierre Puvis de Chavannes and Maurice Denis school of painting. It shows a tall man kneeled and supported himself by the wooden stick, drinking water from a narrow stream, pastured sheep on the meadow in the background. Zak created it in very pale colors; green, orange, yellow, deep blue and brown in an aftermath of Fauvism. But it also recalls to French art since the late of 19th century, which was full of calmness, quietude and romantic feelings. Zak’s "Shepherd" shows loneliness of his life, monotony and resignation like some of Millet’s works.
Zak like his fellows from the "Rytm" used permanent truths by means of traditional iconography; however put them in modern costume.

Eddy is remembered for the courageous purchases he made in 1913 at the Armory Show, the controversial exhibition of Modern art that debuted in New York and was then shown at The Art Institute of Chicago. Eddy not only purchased but also attracted modern art through publications i.e. "Cubists and Post-Impressionism." In 1931, eleven years after his death, the Art Institute of Chicago acquired 23 objects from his collection, naming them the Arthur Jerome Eddy Memorial Collection. Among them was also Zak’s "Shepherd".