Locatelli was born in Toscolano-Maderno, near Brescia, Lombardy. A Midfielder in Vittorio Pozzo's Italian national teams, he appeared in 22 matches for the azzurri, first playing in the first round match in the 1936 Summer Olympics versus the United States  and never appearing on a losing side for the national team. He was also successful in winning the Scudetto with Internazionale in 1938 and 1940. He first played for Brescia between 1933 and 1936 before transferring over to Inter, then called Ambrosiana Milan until 1941 before ending his career with Juventus in 1949 following a move there in 1941.
Locatelli is one of only four Italians to have been doubly honoured at the Olympics and a World Cup.