Gérard Lefranc took up fencing after World War II and honed his skills in the military. He won back-to-back team épée bronze medals for France at the 1958 and 1959 World Championships, and was then selected to represent his country at the 1960 Rome Olympics. There, alongside Armand Mouyal, Yves Dreyfus, Claude Brodin, Christian d’Oriola, and Jack Guittet, he was eliminated in round two of the team épée. He won his only individual national title the following year in the individual épée, as well as a silver medal in the team version at the Worlds. His final major international medal came at the 1962 Worlds, when he finally won the team épée title. Domestically, he won the team épée national title in 1960, 1961, 1964, and 1966. By career, he ran the family industrial business.