Bertini earned 25 caps for the Italy national team between 1966 and 1972. He missed out on the 22-man Italy squad for the 1966 FIFA World Cup, although he was still brought to England by manager Edmondo Fabbri, along with Luigi Riva, as an additional reserve in order to gain experience with the national side. Bertini played in the 1970 FIFA World Cup, where he wore the number 10 shirt, as Italy managed a second-place finish. In the final, he marked Pelé in his movements in depth outside the area, although Brazil eventually defeated Italy 4–1.