The designer once dubbed "the new Versace," a reference to fashion guru Gianni Versace, said he is innocent of all the charges, which he contends are destroying his reputation, The Sunday Times of London reported.
"It's a mistake, I'm just the victim in this whole affair," Mattiolo said. "My name has been unjustly dragged through the mud on the eve of my next collection, in which I hope to make my comeback."
A prosecutor placed the 39-year-old designer under house arrest at Mattiolo's luxurious Rome mansion as Italian finance police investigate the allegations.
The criminal inquiry has captured the interest of the Italian media following the Dec. 5 house arrest order and Mattiolo has struggled to find support in the fashion industry.
"Maybe he'd bitten off more than he could chew," Mattiolo's former business partner, Fernando De Vincenzi, told The Sunday Times.
"Gai Mattiolo is one of us. But creative geniuses are often naive about business," stylist Renato Balestra offered.