He first attended classes with the sculptor Frans Joris, then painters Polydore Beaufaux and Charles Verlat.

[2] In 1883, Leon became one of the founders of the art circle als ik kan ("if I can")[3] in which, in particular, Henry van de Velde began, but after five years he left the group.

[3] At the turn of the 19th and 20th centuries, Brunin participated in exhibitions and auctions in Belgium, France, Germany and the USA.

One of his students was Servais Detilleux [fr], to whom we owe a 1929 Portrait de Madame Léon Brunin.

[4] Contrary to his early work, such as self-portrait Artist in his Workshop, Brunin developed later a more conservative style, inspired mostly by Rembrandt and Henri de Braekeleer.