[3] After joining Bologna in 1995, he became the undisputed first-choice keeper for the club (apart from the 1997–98 season, during which he backed up Giorgio Sterchele); he immediately helped the club obtain Serie A promotion, winning the 1995–96 Serie B title, later helping Bologna to win the 1998 UEFA Intertoto Cup, and subsequently reach the semi-finals of the 1998–99 UEFA Cup and the Coppa Italia.

[9] Antonioli never debuted for the senior side, but was selected in the Italy squad that finished second at Euro 2000, as third-choice goalkeeper, behind Gianluigi Buffon and Francesco Toldo.

[3][10] Antonioli was the first-choice goalkeeper of the Italy national under-21 football team that won the 1992 UEFA European Under-21 Championship; with the Italian squad, he also took part in the 1992 Olympic Games.

[3][10] An experienced and authoritative presence in goal, Antonioli was regarded as one of Italy's most talented and promising goalkeepers in his youth, although several pundits consider him to have failed to realise his potential due to several injuries as well as his character.

Due to his elegant playing style, shot-stopping abilities, reflexes, and excellent goalkeeping technique, he was capable of producing spectacular, decisive, and stylish saves.