Pernice and Guaccero, who is an actress and singer, won the 19th season of Ballando Con Le Stelle, after performing dances including the Argentinian Tango and the Charleston.
The pair had recently confirmed their status as a romantic couple.
Italian-born Pernice shared several posts on Instagram about his win and thanked UK fans for their support.
In September, the BBC apologised to Pernice’s former partner Amanda Abbington and upheld findings of harassment and verbal bullying against him but he was cleared of allegations of physical aggression.
Abbington, who played Mary Morstan in Sherlock, has since said she felt vindicated and that she had “no regrets” after making the complaints.
Pernice said at the time he was “relieved that the allegations that I was threatening and abusive were found not to be true.”