Soncin started his professional career at Solbiatese of Serie C2. He then played for Venezia youth team and then loaned back to Solbiatese for a season, and then for Vigevano in Serie D.
He then moved to Perugia of Serie A, but left for Sambenedettese of Serie C1 after 2 months.
On 2003/04 season, he first played for Fiorentina at Serie B then for Pistoiese at Serie C1. He was loaned to Lanciano of Serie C1 in summer 2004. He enjoy his best season at professional league, scored 21 goals.
On 21 July 2005, newly relegated Atalanta signed him. He made 31 league games in his first full Serie B season, and saw he followed Atalanta returned to Serie A.
He made his Serie A debut on 17 September 2006 against Catania. He just managed to play for Atalanta eight times that season, including one games scored against Triestina at Coppa Italia.
On 27 January 2007, he was on loan to Ascoli, to help the club avoid relegation.
He scored 6 goals for the club, just one goal behind team top scorer Saša Bjelanović, who played 10 more games than Soncin.
At the end of season, Ascoli finished 19th, fail to avoid relegation.
He signed a 2+1 contract with Padova in August 2009. Soncin left Padova at the end of season.
On 13 August 2013 he was signed by Avellino.
On 17 July 2014 he was signed by A.C. Pavia.
On 31 August 2015 Soncin was signed by AlbinoLeffe, on loan from Pavia.
On 24 October 2016 Soncin was signed by Serie D club Montebelluna.