Belgiorno-Nettis was born in Cassano delle Murge in the Province of Bari in Apulia, Italy in 1915 and attended the Turin Military Academy before joining the Italian army and serving in North Africa during World War II. He spent 3 years at an allied POW camp in India. After the war he returned to Italy to complete his studies in engineering at the University of Turin. In 1951 he came to Australia as the employee of Italian engineering firm Electric Power Transmission, (an offshoot of Milan-based Societa' Anonima Elettrificazione), which was constructing powerlines.