In 1970, Giunti was signed by Ferrari primarily for their sports-car team, and won the 12 Hours of Sebring as well as achieving several other high placings. His success earned him a Formula One chance along with Clay Regazzoni, who Ferrari was also trialling at the time. Giunti finished fourth on his debut in the Belgian GP at Spa. Despite his being out-performed by Regazzoni during the remaining races, he was re-signed by Ferrari for the following season.