The 31-year-old completed the move across Turin on Friday, with the defending champions confirming the deal in a brief statement on their official website.
"Juventus football club can today announce that Fabio Quagliarella has completed a permanent switch to Torino football club after a fee of €3.5million, to be paid over the next three years, was agreed by both parties," it read.
Quagliarella started just three games for Juve last season, scoring once, and his departure had been expected.
He was forced to deny rumours that emerged last month linking him with a return to Fiorentina, where he spent a spell on loan in the 2002-03 campaign.
Quagliarella moved to Juve from Napoli in 2010 and has won three Serie A titles with the club.