The Italian has been brought in as a replacement for Andrea Iannone, who will move up to the Ducati factory team from the beginning of next term, and will join Yonny Hernandez in the Pramac line-up.
Petrucci has battled his way back from a fractured left wrist this season, and produced one of his best performances of the season to finish 11th at Aragon on Sunday.
"I am very happy to have reached an agreement with Pramac Racing, a team that has shown great care and ability to promote the growth of young riders," he said. "I am also proud and extremely motivated for the chance to ride a Ducati.
"I will try to give everything to make the most out of this opportunity for which I thank Pramac Racing.
"I also wanted to thank Giampiero Sacchi [IodaRacing Project owner] for giving me the opportunity to start racing at the highest level in MotoGP."
Petrucci currently sits 20th in the riders' standings with four races to go.