The singer will headline the event at London's Roundhouse venue in Camden on September 21.
"I was gutted to not have played at last year's iTunes Festival, so this year is going to be epic," Jessie J told Metro.
"The Roundhouse is one of my favourite London venues. I can't wait!"
Jessie J pulled out of last year's event after breaking her leg and was replaced on the bill by Hard-Fi.
Tickets for the show are free for competition winners, and can be applied for on the festival website.
Other artists confirmed for this year's month-long series of gigs include One Direction, Noel Gallagher's High Flying Birds and Labrinth.
Watch Jessie J's music video for 'Who You Are' below: