Because writing and recording a triple-album set -- and then touring behind it -- apparently isn't enough to keep him busy, Green Day frontman Billie Joe Armstrong has joined NBC's reality singing competition series 'The Voice' as a mentor.

The show's Twitter account broke the news on Thursday night (July 26), tweeting, "Welcome Billie Joe (@BJAofficial) to #TeamXtina! We are ready to rock out in Season 3."

As referenced in the tweet, Armstrong will be a member of Christina Aguilera's team. He joins previously announced Season 3 mentors Michael Buble, Mary J. Blige, and Rob Thomas of Matchbox Twenty.

Armstrong explained his decision in a press release, saying 'The Voice' is successful because "it's not molding artists, it's just giving them a little bit of guidance and direction without giving them a complete makeover" and adding that working with Aguilera is "a lot of fun."

According to the Hollywood Reporter, taping for the third season -- which is set to premiere Sept. 10 -- started this week.

It's a surprising move for Armstrong, but one that will no doubt help Green Day promote their upcoming three-album set, 'Uno!,' 'Dos!,' and 'Tres!,' the first installment of which is scheduled to arrive on Sept. 25.