Avril Lavigne & Cassadee Pope: 'I'm With You' on 'The Voice'!

Avril Lavigne graces the stage during The Voice Season 3 Finale on Tuesday (December 18) at Sony Studios in Culver City, Calif.

The 28-year-old singer joined finalist and devoted fan Cassadee Pope on stage for a performance of her hit song “I’m With You”. Check out the stunning duet below!

During the finale, the winner was crowned. Make sure to find out if Cassadee, Terry McDermott, or Nicholas David took home the title.

Help support Cassadee by buying her tracks on iTunes. She’s already hit number one twice!