Juve, seventh last term after one of the worst ever seasons for Italy's most successful domestic club, have already brought in Marco Storari, Simone Pepe, Jorge Martinez and Leonardo Bonucci while rival clubs have barely entered the transfer market.
The Turin club said in a statement that Motta, who had mixed reviews during a recent 18 month loan spell at AS Roma, would be on loan for the coming campaign and that Juve would then have the option to buy him for 3.75 million euros.
Motta has already joined Juve's pre-season training camp in the Dolomites as Luigi Del Neri's side prepare for an early start to the season with a Europa League third round qualifier first leg scheduled for July 29.
Goalkeeper Storari, signed from AC Milan, is set to play in that game and be Juve's first choice for around three months after Gianluigi Buffon underwent surgery on a herniated disc in his back.
The keeper only played one half of Italy's ill-fated World Cup defence because of the problem but Juve said the 32-year-old's operation had gone well and he would now start a rehabilitation regime.
