McElderry, who won the 2009 series of the competition, will compete in the ITV series alongside famous faces including Erasure's Andy Bell, Midge Ure and Jocelyn Brown.
"I'm alright with performing in front of Rolando and Katherine now. I'm used to being in front of high-profile people after The X Factor, so that makes it a bit easier," the 19-year-old told The Sun.
McElderry, who was recently dropped by record label Syco, added: "I've also been in the environment of having to learn a song quickly and performing it."
Former Pussycat Dolls star Melody Thornton, who is also competing, is keen to impress the judges.
"Singing has so much more to do with performing than it does singing," she said. "I think performance is a strong asset of my mine."
Myleene Klass will host the series, while Jenkins and Villazon will be joined by two more unconfirmed judges.
> Joe McElderry: 'Haters spur me on'
Watch the promo for the new series of Popstar to Operastar below: