The season ten finalist, who fronts a Nashville-based band called Grand Magnolias, will contribute music to the independent film's soundtrack, it was confirmed this week.
Facinelli had earlier explained that he was introduced to McDonald's music through the singer's girlfriend Nikki Reed, who appears with Facinelli in The Twilight Saga movies.
"I heard him on American Idol and I thought he was great, but when I heard the band, it's very distinct and has a voice of its own, and I like the originality of it," he told MTV.
McDonald, who met Reed while filming an American Idol segment at the Red Riding Hood premiere in LA, has now confirmed the collaboration on his Twitter account, telling followers that he is "super pumped" to be working on the project.
The singer, who was eliminated from American Idol last week, also revealed on Twitter that is looking ahead to his music future.
"New songs! I'm thinking about releasing 4 song EP on vinyl that would be available only at independent record stores. Thoughts?" he asked followers on Sunday.
McDonald can be seen alongside the rest of American Idol's Top 11 on this summer's tour.
American Idol airs Wednesdays and Thursdays on Fox.