Toussaint was born in Brussels in 1873 in a family of upper-middle class. When his parents discovered his talent in drawing they helped him to develop it in full.He began studying art with Jean-François Portaels and at the Académie Royale des Beaux-Arts at the age of 15. At the age of eighteen he left for Paris to continue his studies there. He made his study under the well-known Belgian portraitist Alfred Stevens. He specialised in painting portraits of women, still lifes and city-scapes, in the Impressionist, Art nouveau, and Post-Impressionist styles. His works include paintings, water-colours and posters. He is also a famed artist to depict beautiful floral still lifes and interiors, coastal views and seascapes. In this genre his paintings have to be compare with the painters of his epoque the likes of Constant Permeke and Adrien le Mayeur de Merprès, that influenced much his own manner. One of the Belgian art critics of that time Camille Lemonnier said about Toussaint, that he was "one of the painters that broadened the horizon of the peaceful and intimate landscape". Beginning from 1895 Toussaint had been receiving a lot of orders for commercial posters for different official events. He died in the Brussels suburb of Elsene.