In 1971 he made his Formula 1 debut at the Dutch Grand Prix on an STP March after failing to qualify for the Italian Grand Prix in a McLaren-Alfa Romeo and the 1971 season opener in Monte Carlo . At the French Grand Prix in 1971 in Le Castellet, he qualified for the race though, the team had not enough engines. So Galli had to cede his starting place to the Spaniard Àlex Soler-Roig , who was placed worse in training, but raised more sponsorship money.
At the 1972 French Grand Prix, Nanni Galli even contested a Grand Prix for the Ferrari team. He replaced the injured Clay Regazzoni , who had broken his wrist a week earlier during the 1000 km race in Zeltweg during the non-training period at a football game. Galli, who contested the 1972 season with a Tecno V12 , could not recommend himself for further Ferrari assignments with a place in the tenth row and 13th place in the race.
Galli took part in a total of 17 Grand Prix races, most recently in 1973 at the Monaco Grand Prix . However, failures predominated (nine times), which were often due to technical problems. He crossed the finish line eight times, but was not placed in the points. His best result was ninth place at the 1973 Brazilian Grand Prix in Interlagos on the Iso-Marlboro IR1 used by Frank Williams Racing Cars .