Ponti was born in Magenta, Lombardy, where his grandfather had been mayor of the city. Ponti studied law at the University of Milan. He joined his father's law firm in Milan and became involved in the film business through negotiating contracts. Ponti attempted to establish a film industry in Milan in 1940 and produced Mario Soldati's "Piccolo Mondo Antico" there, starring Alida Valli, in her first notable role. The film dealt with the Italian struggle against the Austrians for the inclusion of northeastern Italy into the Kingdom of Italy during the Risorgimento. The film was successful, because it was easy to see "the Austrians as Germans" during World War II. As a result, he was briefly jailed for undermining relations with Nazi Germany.