The midfielder endured a poor spell with the Championship club.
The 27-year-old moved to Elland Road in 2014, but struggled to hold down a regular spot in the first-team. He made just 24 appearances for the Whites in the Championship, and failed to score a single goal.
Having failed to make any appearances during his second season with the club, Bianchi joined the Serie B side on loan in January.
And despite being sent off on his debut, he proved to be a good signing for the team and helped them avoid relegation to the third tier.
Tommaso Bianchi, right, celebrating with Giuseppe Bellusci
And the Yorkshire Evening Post reports that the Bianconeri have decided to take up the option in the loan deal by making the switch permanent, with Bianchi set to sign a three-year contract.
Most United fans will surely reflect that it was the right decision to let the midfielder move on. It is arguably in the middle of the park that the club is strongest in terms of depth, so Bianchi was always going to struggle to regain a place in the team, even if Garry Monk had offered him a fresh chance to prove himself.
The former Sassuolo man's departure may allow Monk more funds to invest in other areas of the squad that require more attention, and will ensure that the likes of Ronaldo Vieira and Kalvin Phillips are not pushed down the pecking order.