Michael Laverty will replace Marco Melandri at the Aprilia Racing MotoGP team in this weekend's German Grand Prix at Sachsenring.
Aprilia announced earlier today that it had parted ways with Melandri after a disappointing season by the Italian rider.
Laverty will return to MotoGP after having competed in the championship with Paul Bird Racing least season.
The Northern Irishman is part of Aprilia's test team.
He will partner Alvaro Bautista this weekend.
"I'm excited to be back on the MotoGP grid this weekend of the German GP," said Laverty. "Competing against the regular guys racing MotoGP is a tough task, but I am relishing the opportunity.
"I have been riding with the Aprilia test team so I am comfortable with the Aprilia RS-GP machine and the Bridgestone tyres. Firstly I must adapt the race bikes to suit me and then look to keep progressing throughout the weekend.
"Alvaro has been riding strongly in this first half of the season and I have witnessed some great development work through the test team. I now look forward to being a part of the racing team."
Laverty made his MotoGP debut last year and has a 12th place finish as his best result.