Leon De Smet studied at the Ghent Royal Academy of Fine Arts with his brother Gustave De Smet. Leon and Gustave belong to the second group of Sint - Martens - Latem, the art group that went to live in the region around Sint - Martens - Latem to be in touch with the simplicity of the Lys. Leon was there with the artists Valerius De Saedeleer, Maurice Sys, Permeke, Frits van den Berghe, Gustave Van de Woestyne and his brother Charles Van de Woestijne, a poet.

At the start of the First World War, Leon fled to Britain, where he had great fame, he was given a solo exhibition in January 1917 at the Leicester Gallery in London. When he returned to Belgium in 1920 he had a major exhibition in the Brussels Galerie Georges Giroux. In 1953 he was honored in the Ghent Museum of Fine Arts with a large individual exhibition.

His is classified as impressionist, expressionist and pointillist. He painted mostly with keys, as in The Lovers (1911), but he also had periods where he painted large areas such as Lady with Fan (1924). His color palette is usually somewhat more muted, although he created a wide variety of colors in his works. His compositions are mostly quite balanced.

Outside the Groeningemuseum in Bruges and the Royal Museum of Fine Arts in Antwerp many of his works are in the Ghent Museum of Fine Arts. There was also, at the initiative of Jeanne Baeckelandt, a museum dedicated to the artist Deurle. Here one finds various objects and information from and about the artist and a number of important works.