Marconato joined Benetton Treviso's youth team in 1990 and with them he won three juniors titles between 1991 and 1994. He made his debut in the Serie A with the senior team of Benetton Treviso in the 1993-94 season, but he did not have a place in Treviso's roster, so he was loaned to Padova, where he demonstrated his talent. In the 1996-97 season, he returned to Treviso and Benetton coach Mike D'Antoni gave him a more important role in the team; and that season Marconato won his first Italian Championship. After winning the Italian SuperCup title and MVP in 1997 and the Saporta Cup in 1999, he was named the MVP of the Italian Cup Final Eight in 2000 (won by Benetton).
In the following years, he won two more Italian championships (2002, 2003), three more Italian Cups (2003, 2004, 2005) and played at two Euroleague Final Fours (2002, 2003). During his last season with Treviso, Marconato was also the captain of the team. In the summer of 2005, he moved to the Spanish ACB League club FC Barcelona, together with his Italian national team teammate Gianluca Basile.