X-Factor finalist Wagner is the latest addition to the line-up for Bearded Theory 2011, which runs from 13-15 May at Kedleston Hall, Derbyshire.
He's set to perform in the Sunday lunchtime slot on the Second Stage, continuing a trend set by The Cheeky Girls at last year's event.
Rich Bryan, from promoter Spring Music, said: “Bearded Theory Festival is all about having fun. We took a massive gamble on booking The Cheeky Girls last year and it was a rip-roaring success. This year we can't wait for Wagner to be THE talking point at the festival.”
The Whip, reggae fusion band The Skints, Sonic Boom 6 and Cosmo Jarvis also join the line-up of the three-day festival.
The Last Republic, Mama Rosin and Dirty Revolution complete the latest wave of acts.
Weekend tickets are still on sale at £70 for adults and £34 for under 16s, with other options available.