Cornacchini initially played for
Fano between 1981 and 1987, and also had a spell on loan with
Foligno during the 1985–86 season. After stints with
Reggiana and
Virescit Bergamo, he joined
Piacenza in 1989, where he scored 36 goals in two seasons, finishing as the top scorer in
Serie C1 on both occasions, and helping his team to win promotion during the 1990–91 season. The following season, Cornacchini returned to Serie C1, joining
Perugia, where he scored 59 goals over three seasons, finishing as the top scorer of his division in the first two, and later helping his team achieve promotion to Serie B as the league's second-highest goalscorer, behind only Giovanni Pisano. He joined
Bologna ahead of the 1995–96 season, although he was unable to replicate his performances at Perugia. Notwithstanding this, the following season, he was acquired by
Vicenza manager
Francesco Guidolin (whom he later described as his best manager in 2019), where he won the
1996–97 Coppa Italia, contributing to his team's victory by scoring important goals in the competition, in particular against
Genoa, and later against his former club Bologna in the semi-finals; he also started in the victorious two-legged
final against
Napoli. and scored his only Serie A goal on 20 April 1997, in a 4–1 win over Perugia in Reggio Emilia. In total, he obtained 21 appearances in his two seasons in the Italian top flight. In February, after only making seven appearances for the latter club, he joined
Ternana in Serie C1, helping the club obtain promotion with three goals in 13 appearances under manager
Luigi Delneri. After returning to Padova, now in Serie C1, he ended his career in the lower divisions of Italian football, with
Gubbio, Fano, and finally
Cagliese, retiring at the end of the 2002–03 season. ==Style of play==