A friend and compatriot of Tristan Tzara, he was among the founders of the Dadaist movement, established in 1916 at Cabaret Voltaire in Zurich, Switzerland, by a group of exiled poets, painters and philosophers who were opposed to war, aggression and the changing world culture. In 1922, Janco returned to Romania, where he gained fame as a painter and architect. In 1941, fleeing the Nazis, he moved to Palestine, and was one of the founders of the New Horizons Group (1948). The Janco-Dada Museum, which opened in 1983, features Janco's work and explores the history of the Dada movement.
In 1953, Janco established the Ein Hod artists' village near Haifa, Israel. Towards the end of his life he helped found the Dada museum in Ein Hod which bears his name. The museum houses Janco's art, explores the history of Dadaism and mounts changing exhibitions.