De Graffenried was born in Paris, the son of Swiss Baron Leo de Graffenried and his American wife Irma Stern. He began his racing career in 1936, driving his own Maserati voiturette. Some of his most memorable results came at his home track: the challenging, cobbled, street circuit at Bremgarten near Bern. He won the 1949 British Grand Prix, a year before the FIA World Championship began. In that inaugural year de Graffenried contested four of the season's seven races, with mixed results. He continued to drive in occasional races over the next six years, with his best finish being fourth place at the 1953 Belgian Grand Prix.