LOS ANGELES, April 29 (Reuters) - Singer Gwen Stefani will be sitting alongside fellow star musicians Pharrell Williams, Adam Levine and Blake Shelton in the forthcoming season of NBC's singing talent competition "The Voice," the Comcast Corp-owned network said on Tuesday.

Stefani, 44, who rose to fame as the blonde-haired sultry lead singer of Southern California rock group No Doubt, will join Pharrell in taking over from current judges, Colombian singer Shakira and R&B star Usher.

NBC also said that Christina Aguilera, one of the show's original four celebrity coaches, will return for the eighth season next year. She took a hiatus from "The Voice" after season five, and is expecting a child.

The Emmy-winning show has outpaced competition from Fox's reality singing contest "American Idol," averaging about 13.8 million viewers per episode this season, trumping "Idol" by about 3 million viewers per episode.

The show's celebrity panel of judges led by Aguilera, Maroon 5 frontman Levine and country music star Shelton, has been credited with helping it draw viewers.

"The Voice" is also considered a coveted spot to promote songs, such as Maroon 5 and Aguilera's "Moves Like Jagger" that became a hit in 2011, after the singers performed it on the show.

Grammy-winning Stefani is best known for No Doubt hits including "Don't Speak" and "Hey Baby," and her solo career with songs such as "Hollaback Girl." The singer, who also has a successful clothing line, L.A.M.B., is returning to the spotlight after the birth of her third child.

She will join fellow "Voice" newcomer Pharrell to perform on the show's telecast next week, each performing their latest hits. The duo performed together during Pharrell's set earlier this month at the Coachella Valley Music and Arts festival.

(Reporting by Piya Sinha-Roy; Editing by Mohammad Zargham)