On his return to France, he took acting and mime lessons at the Étienne Ducroux school, where he met Marcel Marceau.

Although his act still involved elements of his early years as a clown (such as juggling) he was mostly recognized because of his mastery of the French language.

Devos is a leading character in Alejandro Jodorowsky's surrealist 1957 debut short film Les têtes interverties (a mime adaptation of Thomas Mann's 1940 play The Transposed Heads).

Perhaps his best-known international appearance is a cameo in Jean-Luc Godard's Pierrot le Fou 1965 as a man sitting on a harbourside who is obsessed with the memory of a mysterious love song.

Devos was born of French parents and raised in France, but was always respectful of his country of birth and once quipped that he was still, after all, a "fake Belgian".