Season 8 of NBC's "The Voice" kicks off next month and we already know who the celebrity mentors will be. Sources close to the singing competition show told Us Weekly that pop stars Ellie Goulding, Meghan Trainor, Nick Jonas and Lionel Richie have signed on as advisors.

Richie, who served as a mentor in Season 2 to Christina Aguilera's team, will now help out Team Pharrell Williams. Goulding will assist Adam Levine's team, Jonas is Team Aguilera and Trainor will be a part of Team Blake Shelton.

The mentors help out during the battle round of the competition and provide tips to the contestants. Season 8 will be Aguilera's first time back in the red chairs since she left two seasons ago. The "Beautiful" singer, who is working on her eighth album, took a break from the show to give birth to her daughter, Summer Rain.

Aguilera and her fiancé Matthew Rutler welcomed the little girl in August. The now mom of two recently shared a photo of her daughter wearing a hot pink dress with a diaper that had the words "Lil Diva" written across the bottom.

"Watch out... another one's getting ready to conquer the world! #driven #diva2," she captioned the photo.

While Aguilera was on leave, she was replaced with Shakira for Season 6 and Gwen Stefani for Season 7. NBC announced back in October that Aguilera was coming back.

"New baby. New music. New season of @NBCtheVoice. Bringing #FireAndFun to all, can't wait for 2015!" Aguilera tweeted in October.