|Date of birth||5 April 1988|
|Place of birth||Guastalla, Italy|
|Height||1.86 m (6 ft 1 in)|
|2007–2009||→ Sambonifacese (loan)||55||(0)|
|2010||→ Pro Sesto (loan)||14||(0)|
|2014–2015||→ Cittadella (loan)||0||(0)|
|2015–2016||→ Lugano (loan)||11||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 1 August 2014.
Born in Guastalla, Emilia–Romagna, Valentini started his career at Mantua, Lombardy, about 30 km (19 mi) away. Primary a youth team player, he was awarded a no.88 shirt in 2006–07 Serie B. He was loaned to Sambonifacese and won the promotion playoffs of 2007–08 Serie D. The club then signed him in co-ownership deal. In June 2009, he was bought back from the San Bonifacio based club. Since returned to Mantova, he was selected to Italy under-21 Serie B representative team twice, for internal friendlies, both as white team keeper against the blue team. In January 2010, he was loaned to Pro Sesto.
After Mantova went bankrupt, he was signed by Pro Belvedere Vercelli (and later merged with Pro Vercelli to become F.C. Pro Vercelli 1892) He was the first choice of the team, ahead Marzio Dan who was the first choice for PB Vercelli in the last season.
- "L'ESITO DELLE COMPROPRIETA'". AC Mantova (in Italian). 25 June 2009. Archived from the original on July 26, 2012. Retrieved 1 January 2010.
- "Match Report" (pdf). Panini Digital (in Italian). Published by Lega Serie B. 20 October 2009. Retrieved 21 October 2010.
- "Match Report" (pdf). Panini Digital (in Italian). Published by Lega Serie B. 24 November 2009. Retrieved 12 August 2010.
- Sica, Stefano (20 January 2010). "UFFICIALE: Pro Sesto, dal Mantova c'è Valentini". Tutto Mercato Web (in Italian). Retrieved 21 October 2010.
- Zalamena, Andrea (19 July 2010). "Pro Belvedere, ecco Valentini, Corsino e Meregalli". Tutto Mercato Web (in Italian). Retrieved 21 October 2010.