Bulgarelli played three matches for Italy at the 1960 Summer Olympics.

He made his senior debut for the Italian national team at the 1962 World Cup, on 7 June, scoring two goals in a 3–0 win in Italy's final group match against Switzerland, which were unable to prevent the team from being eliminated in the first round.
With these goals, he became the youngest ever goalscorer for Italy at the FIFA World Cup, at the age of  21 years and 226 days.
He played all three matches for Italy at the 1966 World Cup.
Throughout the tournament, he also featured as the team's captain ahead of Sandro Salvadore in the team's infamous and historic 1–0 defeat to North Korea in Middlesbrough, on 19 July, which led to the Italians' elimination from the World Cup.
During the match, Bulgarelli was forced off due to a knee injury when the score was still 0–0, leaving the Italians a man down for the remainder of the match, as substitutions were not permitted at the time.
His only other appearance as Italy's captain came on 18 June 1966, in a friendly match against Austria.

He was a member of the Italy squad that won the 1968 UEFA European Championship on home soil, where his leadership and experience played an important role in the team's success, even though he did not appear throughout the final stages of the tournament; his last international appearance came against Romania, in 1967.
He made a total of 29 appearances for the Italy national side, scoring 7 times.
Bulgarelli played three matches for Italy at the 1960 Summer Olympics.
He made his senior debut for the Italian national team at the 1962 World Cup, on 7 June, scoring two goals in a 3–0 win in Italy's final group match against Switzerland, which were unable to prevent the team from being eliminated in the first round. With these goals, he became the youngest ever goalscorer for Italy at the FIFA World Cup, at the age of  21 years and 226 days. He played all three matches for Italy at the 1966 World Cup. Throughout the tournament, he also featured as the team's captain ahead of Sandro Salvadore in the team's infamous and historic 1–0 defeat to North Korea in Middlesbrough, on 19 July, which led to the Italians' elimination from the World Cup. During the match, Bulgarelli was forced off due to a knee injury when the score was still 0–0, leaving the Italians a man down for the remainder of the match, as substitutions were not permitted at the time. His only other appearance as Italy's captain came on 18 June 1966, in a friendly match against Austria.
He was a member of the Italy squad that won the 1968 UEFA European Championship on home soil, where his leadership and experience played an important role in the team's success, even though he did not appear throughout the final stages of the tournament; his last international appearance came against Romania, in 1967. He made a total of 29 appearances for the Italy national side, scoring 7 times.
Giacomo Bulgarelli