He started his professional career in the A.C. Milan youth system. He was then loaned to Serie C1 teams Livorno, SPAL, Monza (also co-ownership) and L'Aquila (also co-ownership) between 1999–2003 and Serie B team Avellino in 2003/04 season. His 50% registration rights were bought by Parma in 2004 for €180,000 that became full ownership in 2005 for undisclosed fee.
On 8 July 2010, Zaragoza made the purchase option, for €2 million and signed Contini on a three-year deal.
On August 8, 2011, after a year and a half in Spain, he returned to Italy, taken from Siena on a season-long loan for €300,000 with option to buy the registration rights. In July 2012, Contini signed a permanent deal with Siena, for about €1.3 million. Six months later, he joined Atalanta. In the August 30, 2013, he goes on loan to Juve Stabia.