At international level, Mussi won 11 caps for the Italy national football team between 1993 and 1996 under manager Sacchi. He participated at the 1994 FIFA World Cup with Italy, where they reached the final, only to lose to Brazil on penalties. He made 3 appearances during the tournament, including one in the final defeat, picking up an injury during the match; he was replaced by Luigi Apolloni. He also notably set up Roberto Baggio's last minute equaliser against Nigeria in the round of 16, which enabled the Italians to win the match in extra-time with a Baggio penalty and advance to the quarter-finals. He also took part at Euro 1996, making 3 appearances as Italy were eliminated in the group stage.