He and Ravel belonged to the Paris avant-garde artistic group known as Les Apaches for whose meetings he was sometimes the host.
He recorded his long acquaintance with the composer in an essay, "L'Époque Ravel".
Ravel dedicated the first of his Trois Chansons to him in 1915.
Klingsor was also a painter (exhibiting from 1905 at the Salon d'Automne and being awarded the Prix Puvis de Chavannes in 1952).
His visual art was reviewed twice by Guillaume Apollinaire: In 1906, he called Klingsor's attempts "Merde!" but in 1908, he was kinder, stating: "Klingsor animates his painting with the same sentimental delicacy that gives his poetry its somewhat contrived, dated charm.
For my part, I prefer the poet to the painter.” He was also the author of several studies on art, and a composer in his own right, with several collections of melodies, four-part songs, and piano music.