The former Manchester United and Real Madrid defender has agreed to take up a new challenge after two years in France
The Serie A side have not disclosed any details about the defender's contract, but reports in the country suggest the 33-year-old has been tied down to a one-year deal.
Heinze announced at the end of the last season he would depart Marseille after spending two years at the Stade Velodrome.
His transfer comes on the same day as Barcelona announced they had reached an agreement with Roma for the sale of striker Bojan Krkic.
The Argentina international will now experience his fifth different European league in his career, having previously played in Spain, Portugal, France and England.