After doing his artistic studies at the Academy of Saint-Josse-ten-Noode (Brussels), Georges Lemmen became a member of the "XX group" (1884 -1893) where the main avant-gardes of the time converged. He then became a critic for the review L’Art Moderne.

Around 1890, he adopted the pointillist technique and produced a series of portraits before gradually turning to the decorative arts, in the line of W. Morris and adopting less and less figurative ornamentation, which made use of the line "suddenly. whip ”(1894). In this field, he created - especially for the gallery owners Siegfried Bing (L'Art Nouveau) and for Julius Meier-Graefe (La Maison Moderne) - posters, bookplates, ornaments, tapestries, wallpapers, jewelry, tiles, mosaics and ceramics. He also created an original typeface for the edition of Thus Spoke Zarathustra produced by his friend Henry Van de Velde (1899 - 1900). At the same time, his painting was similar to the Art Nouveau style.

From 1900, Lemmen then approached the aesthetics of the Nabis and produced an intimate painting, of mainly family scenes, before turning to the subject of the “Bathers” (1906). These are in pastel colors: he made a trip to Beaulieu-sur-mer, in the south of France, in 1911, during which he discovered the colors of the Mediterranean. Back in Brussels, he organized an exhibition of his work which was a great success (1913).
His paintings, for the most part, are characterized by a simplified line, by a stylized drawing and by warm and contrasting tones, but they are muffled, and retained throughout his development the influence of Degas, Toulouse Lautrec and Seurat.
He died during the war, in Ukkel (Brussels) in 1916.