The Italian crashed in first practice at Misano a fortnight ago, and was ruled out of the race having fractured the T3 vertebra in his upper back.
Determined to race at Aragon - where he started on the front row and finished fourth in 2015 - Iannone was cleared by doctors on Thursday to compete.
However he is braced to be riding in pain.
"Over the last few days I've been trying my best to recover by resting after the crash at Misano, but I've still got a bit of pain in my back," he said.
"For sure I'll be trying to race and will try and do my best, as always.
"I hope to be in quite a good shape and to be able to keep the pain under control, because I think that this can be a positive circuit for us, seeing as we had a great race here last year."