The award-winning country group joins the Miley Cyrus movie.

ET has learned that RASCAL FLATTS has been confirmed to perform in Disney's upcoming 'Hannah Montana: The Movie.'

In other Rascal Flatts news, guitarist JOE DON ROONEY and his wife, TIFFANY FALLON, a former Playboy Playmate, are the proud new parents of their first child, a son named JAGGER DONOVAN ROONEY. The baby was born on Saturday, it was reported by the Associated Press.

"We are absolutely blown away by this little miracle gift that God has given to us," Rooney and Fallon said in a statement. "We can't wait to see what the future has in store for baby Jagger and our new family!"

Rascal Flatts is the reigning winner of the Academy of Country Music, Country Music Association and American Music Assocation's Vocal Group of the Year awards.

'Hannah Montana,' which is currently filming in Tennessee, stars MILEY CYRUS and BILLY RAY CYRUS, and is slated for release in 2009.