From the mid-1980s until the late 1990s Cédric Plançon was one of the best weightlifters in France. He won his first national title in 1986 before winning bronze in the light-heavyweight class at the 1987 Mediterranean Games. Plançon returned to the Mediterranean Games four years later to win silver in the same weight class, securing himself a place on the French Olympic team. At the 1992 Barcelona Games he competed in the middle-heavyweight event where he placed ninth. Plançon then participated at the 1996 Atlanta Olympics where he finished 19th. After his competitive career he continued to be active in the sport as a trainer whilst also working for the telecommunications company France Télécom.