Playing for the France national team, Petit earned 63 caps and scored six international goals in his career and won the 1998 FIFA World Cup and UEFA Euro 2000. He scored twice in the 1998 World Cup, the first from a powerful shot from just outside the box against Denmark, which turned out to be the match winner, and a second in the final against Brazil. The goal he scored in the final was particularly memorable, as he had embarked on an optimistic run across field before calmly slotting in the goal in the final minute of regular time. That same goal happened to be the 1,000th goal in the history of the French Football Federation, and the last World Cup goal of the 20th century. France won the match 3–0. An earlier Petit corner kick had set up Zinedine Zidane's header for France's first goal. Petit was also part of the 2002 World Cup squad, though France failed to advance past the group stages and failed to score a single goal in three matches during their defence of the trophy.
He starred as himself, in a Christmas special episode of British police show The Bill in 1998.