Damian Cudlin will replace Loris Capirossi at the Pramac team during this weekend's Japanese Grand Prix.
The 28-year-old Australian has no MotoGP experience and has taken part in just one world championship race, when he competed in the Moto2 event in Germany in 2010.
Cudlin, the reigning IDM German Supersport champion, replaces Capirossi after the Italian dislocated his shoulder in the previous race in Aragon.
"It's hard to put into words what this opportunity means to me," said Cudlin. "I've dreamed about starting in MotoGP since I was a boy, and until now it's been just that- a dream. Now it's become a reality and to be honest, I'm still in shock!
"I'm under no illusions about how difficult this race will be. I've never ridden a real MotoGP bike before and I've never been to Motegi either, so realistically my expectations can't be too high. I just want to do the best job I can, enjoy the experience, and just see what happens.
"I've really got nothing to lose, so why not? I don't know what I've done to deserve this. I still can't believe I'll be replacing Loris Capirossi- I had posters of him on my wall as a kid! I just want to thank Sito Pons for recommending me, the Pramac Racing Team for giving me a chance, and also my current BMW Team for allowing me to use this opportunity. I hope I can make everyone proud that they took a chance with a guy like me."