Valentino won a bronze medal at lightweight at the 2004 European Amateur Boxing Championships in Pula, Croatia.
He participated in the 2004 Summer Olympics. There he was stopped in the quarterfinals of the Lightweight (60 kg) division by Kazakhstan's eventual bronze medalist Serik Yeleuov.
At the 2005 World Amateur Boxing Championships he once more won bronze. At the 2007 World Amateur Boxing Championships he at last made it to the finals beating North Korean Kim Song-Guk but lost to Frankie Gavin of Great Britain. Valentino qualified as a lightweight for the 2008 Beijing Olympic games. In 2009, Valentino won the World amateur championship in the lightweight class. In 2011, Valentino was a bronze medalist in the lightweight class at the 2011 World amateur championships.
- 2004 Athens Olympic games
- 2007 AIBA World Amateur championships
- 2008 Beijing Olympic games
- 2009 AIBA World amateur championships
- 2011 AIBA World amateur championships in Baku
- 2012 Olympic Games in London