He was born in Temesvár, Austria-Hungary (now Timișoara, Romania), He studied at the Academy of Fine Arts in Budapest (1932–33).

He moved to Paris in 1934 and entered to the atelier of the famous poster artist Adolphe Cassandre (1935–36).

He worked as a painter, sculptor and graphic designer, but is best remembered for his cartoons, whose subtle humor and wide influence bear comparison to those of Saul Steinberg.

François initially worked for French leftist newspapers (Le Nouvel Observateur) and illustrated books by authors such as Jacques Prévert, but gradually reached a larger audience, publishing in leading magazines of the United Kingdom (Punch) and the United States (The New Yorker).

He also did a masterpiece cover illustration of the 1965 UK Penguin paperback edition of Lord of the Flies.