The 32-year-old singer will reclaim her judge's chair on the next season of the singing contest, ousting current mentor Shakira, said the Hollywood Reporter.
Aguilera left the show in 2012 after three seasons to promote her latest album 'Lotus'.
It is still unclear whether Cee Lo Green, who also departed last year, will be returning alongside her.
Producer Matt Burnett confirmed Shakira's departure and explained change was a natural progress when working with successful recording artists.
"Everybody can't coach for life because when you have people with current recording in the game, this is not their job.