Sissoko, 26, has signed a three-year deal and was presented by PSG coach Leonardo on Thursday afternoon.
Born in France, Sissoko has never played in Ligue 1 - emerging through Auxerre's youth academy but leaving before playing a match.
From 2003, he spent two years with Spanish side Valencia before joining Juventus via Liverpool.
Sissoko, who missed the end of the Italian season after having knee surgery in March, will be playing under former Milan coach Leonardo.
At Thursday's news conference, Sissoko announced that he aims to establish himself with PSG before considering an international return for Mali.
Having also bought goalkeeper Salvatore Sirigu from Palermo, a 24-year-old with two caps for Italy, the moves indicate PSG's determination to establish themselves as a major force following the arrival of Qatar Sports Investments (QSI) as majority shareholders.
The club have now made seven signings this summer, with Nicolas Douchez (Rennes), Kevin Gameiro (Lorient), Milan Bisevac (Valenciennes), Blaise Matuidi (Saint-Etienne) and Jeremy Menez (Roma) already having put pen to paper.
Mali midfielder Mohamed Sissoko has joined French side Paris Saint-Germain from Italy's Juventus.