Jean-Paul Belmondo was born in Neuilly-sur-Seine, a suburb of Paris, on 9 April 1933. Belmondo's father, Paul Belmondo, was a Pied-Noir sculptor who was born in Algeria of Italian descent, whose parents were of Sicilian and Piedmontese origin. His mother, Sarah Madeleine Rainaud-Richard, was a painter. As a boy, he was more interested in sport than school, developing a particular interest in boxing and soccer.
Belmondo made his amateur boxing debut on 10 May 1949 in Paris when he knocked out René Desmarais in one round. Belmondo's boxing career was undefeated, but brief. He won three straight first-round knockout victories from 1949 to 1950. "I stopped when the face I saw in the mirror began to change", he later said.
He did his National Service in French North Africa where he hit himself with a rifle butt to end his military service.
Belmondo was interested in acting. His late teenage years were spent at a private drama school, and he began performing comedy sketches in the provinces. He studied under Raymond Giraud and then attended the Conservatoire of Dramatic Arts when he was twenty. He studied there for three years. He probably would have won the prize for best actor, but he participated in a sketch mocking the school, which offended the jury; this resulted in his getting only an honourable mention, "which nearly set off a riot among his incensed fellow students" in August 1956, according to one report. The incident made front-page news.