A native of Pesaro (Marche), he started his bike racing career in 1928, on a Benelli 175cc.

He won the 1939 500cc European Championship on a Gilera, with victories in the German, Swedish and Ulster Grand Prix.

[2] He participated in one Formula One World Championship Grand Prix on 3 September 1950, when he finished second and scored 3 championship points, his points being halved as he shared the drive with Alberto Ascari.

Serafini remains the only Formula One driver to have scored a podium finish in every World Championship Grand Prix they entered.

He retired from racing full-time after sustaining serious injuries during the 1951 Mille Miglia, which required multiple operations over several years.