Ariana Grande is officially joining season 21 of as a coach and she's now filmed her first promo video for the NBC competition series. The 28-year-old singer shared behind-the-scenes photos and videos of herself shooting the sketch with her fellow coaches, Blake Shelton, Kelly Clarkson and John Legend. «Hello and screaming!!! cannot wait for everyone to see our first promo tomorrow for season 21 of @nbcthevoice!!! it’s… the most ridiculous and fun,» Grande captioned her post on Instagram.