Billancourt, discovered graffiti in New York in 1971 while studying architecture in Paris. Back in France, he developed the life-size stencil technique, which he began putting up at night on the walls of Paris in 1981, under the name Blek le Rat. The black rat, his first motif, became his recurring signature.

A pioneer of stencil art and modern street art, he directly influenced a generation of urban artists, including Banksy, who has publicly acknowledged his influence.