"We are thrilled to welcome Usher and Shakira to The Voice. The addition of these popular iconic artists continues the tradition established by Christina, CeeLo, Adam and Blake," NBC Entertainment chairman Robert Greenblatt said.
NBC cited The Voice's new twice-a-year broadcast schedule as the reason why Aguilera and Green -- who are both expected to return to the show down the road -- will be taking the reality singing competition's fourth edition off.
Aguilera is releasing a new album, Lotus, on November 13 and going on tour, while Green is developing new music and a new NBC sitcom based on his life.
"Doing two back-to-back cycles of this show requires a tremendous amount of time, and we are happy to accommodate the commitments made by Christina and Cee Lo. The participants on our show benefit from our coaches' expertise and their continued success in the music business allows for significant new contributions to the contestants when they return," Greenblatt said.
"Having award-winning artists as coaches means they need to be able to tour. Whether in the red chair or on tour, our coaches have their chairs for life. This is exactly why, after three seasons, we needed to allow them to rotate out so they can get on the road amongst their fans. Meanwhile, we're incredibly excited to have singular artists like Usher and Shakira joining the fold," The Voice executive producer Mark Burnett added.
Aguilera and Green are both pledging to return to The Voice following their hiatus.
"I am so proud of being part of the show from the beginning... As I have expressed since day one of the show, that I am a singer and performer first and I am so excited to get back to that love. Since this year NBC and The Voice have decided to tape back-to-back seasons, requiring a full-year commitment, it is important for me to take Season 4 off, allowing me to support my music that my fans have been waiting for," Aguilera said. "By pursuing my first passion of music during the break, I am also able to come back and offer even more to my team on The Voice in the future."
"Thank you NBC for supporting my decision to take this Season 4 hiatus! It says that I'm seen and respected as a complete artist and not just a cast member. I'm highly enthusiastic about focusing my undivided attention on my additional endeavors and interests," Green said. "I will return for Season 5 and will be watching Season 4."