Mandorlini debuted with FC Turin as a professional on February 4, 1979. 1980 He left Turin and moved to Atalanta in the Serie B. 1981 to 1984 he played in Ascoli Calcio. In 1984 he then signed with Inter Milan, where he played until 1991. In the shirt of Inter he won the 1989 Serie A and the 1991 UEFA Cup. In Udinese Calcio Mandorlini played from 1991 to 1993 and also finished his career there.
Mandorlini began his coaching career in 1993 at the ASD Manzanese that was playing in the D series. He could not prevent the descent of the association through the play-offs though. Then he was up to 1998 assistant coach at Ravenna Calcio. From 1998 to 1999, he coached the U.S. Triestina. In 1999 he began his work at Spezia Calcio and blied there until 2002. With Spezia, he won the then Serie C2 (now Lega Pro Seconda Divisione ) in his first season 1999/ 2000, 2002 he missed with Spezia to promotion to Serie B is under. After he moved to Vicenza Calcio 2002 and reached the 8th place in the Serie B 2002/2003 season, he started work at Atalanta Bergamo. He survived the relegation and remained with Atalanta in Serie A, but he was released because of poor play.
In January 2006, he was hired at Serie B club FC Bologna, but was released two months later. In December 2006 he took over the Calcio Padova in Serie C1 (now Lega Pro Prima Divisione ). With the club Mandorlini would rise almost succeeded, after he brings him out of the relegation places. In July 2007 he went to the coach of the Serie A season 2007/2008 against AC Siena, but was dismissed by agreement of both parties on 12 November again.
In 2008 he was the first Ascended into Serie B club Sassuolo Calcio U.S., he could lead the 7th Place. In June 2009, but he left Sassuolo again.
In November 2009, he took over the Romanian club CFR Cluj, who plays in the Romanian first division league 1. In May 2010 he won with CFR Cluj Romania's Double. The Romanian Cup Cupa României and the championship are the first major success as a trainer for Mandorlini. He was released on September 13, 2010 due to lack of success. Cluj was 2010/2011 in the Champions League with Bayern Munich, FC Basel and AS Roma in Group E.
On 9 November 2010 Mandorlini has signed a contract with Hellas Verona. He inherited the unsuccessful Giuseppe Giannini. 11 October 2011 his contract with Verona has been extended until 2014.
- Italian Champion 1988/1989
- Italian Supercup final 1989
- UEFA Cup Winners' Cup 1990/1991
- Serie C2 in 1999/2000 with Spezia Calcio
- Romanian champions 2009/2010 with CFR Cluj
- Winner of the Romanian Cup Cupa României 2009/2010 with CFR Cluj