The couple is "really excited to take this next step!," People's source told the mag Thursday.
"The Voice" coach will be taking off Season 6 of the show, which begins airing next week, with Shakira once again sitting in that bright red seat.
Aguilera's already mom to Max, 6, her child with ex-husband Jordan Bratman, a music producer. The two, whose divorce was final in 2011, share custody of the boy.
On Valentine's Day, Xtina posted a picture of herself holding hands with Rutler in a tropical setting, flashing her new engagement ring. "He asked and I said ......," the caption read. She and Rutler, who works in film, met in 2010 on the set of "Burlesque."
Aguilera's rep did not immediately respond to a request for comment.