|Date of birth||18 May 1977|
|Place of birth||Cesena, Italy|
|Height||1.80 m (5 ft 11 in)|
|Jan. 2004||→ Genoa (loan)||10||(1)|
|2005||→ Ternana (loan)||7||(1)|
|* Senior club appearances and goals counted for the domestic league only.
† Appearances (Goals).
Comandini joined the youth academy of his hometown team A.C. Cesena, and made his full debut for them in Serie B during the 1995–1996 championship. After appearing once during the season he transferred for a year to Serie C1 side Montevarchi, returning in 1997–1998 to newly relegated Cesena. There he played regularly throughout the season, contributing to the team's promotion back to Serie B.
In 1998 Comandini signed to join Vicenza; the contract specified that he would first spend another season with Cesena, for whom he scored 14 times during the season. At Vicenza he was the top scorer during the 1999–2000 season, his 20 goals contributing to the team's championship title and promotion to Serie A. At the season's close he was sold to A.C. Milan for around 20 billion lire.
In June 2001, Comandini was sold to Atalanta for 30 billion lire; team-mate Luigi Sala for 7 billion lire.; team-mate Luca Saudati for 18 billion lire as part of Cristian Zenoni and Massimo Donati's deal to Milan.
He scored four times for Atalanta during 2001–2002, and appeared in ten games during their 2003–2004 campaign, before transferring to Serie B side Genoa in January 2004. He returned later that year to Atalanta, for whom he appeared twice in Serie A, before a January 2005 transfer to Ternana, where he made seven appearances.
In 2006, following persistent physical problems and at age 29, Comandini retired from professional football. He moved back to Cesena, where he opened a restaurant and played for the Polisportiva Force Vigne, an amateur side founded by his father Paolo in 1983 and affiliated to the Italian amateur sports federation Centro Sportivo Italiano.
Comandini was a member of the Italy Under 21 national side during their 2000 UEFA European Under-21 Football Championship. Comandini appeared 19 times, usually as a second striker behind Nicola Ventola, in the team's successful campaign and with them won the championship title in 2000.
The same year, being under 23 and having never appeared for the full Italian national side in a World Cup, he was eligible to represent Italy at the summer Olympics. He appeared in four games including the quarter-final exit to Spain.
- Pietro Serina (30 June 2001). "Comandini, Sala, Dabo: l' Atalanta si fa grande". La Gazzetta dello Sport (in Italian). Retrieved 27 April 2010.
- Calpietra, Alessio Gianni Comandini: "Ho lasciato il calcio perchè è un ambiente non sempre limpido", Tutto Mercato, 6 October 2006
- Player stats at Fifa official website