Jewel has described The Voice coach Christina Aguilera as an "undeniable talent".
The 'Stronger Woman' singer will serve as a mentor for Aguilera's team on the second season of The Voice, which currently airs Wednesday nights on NBC.
Speaking to social media correspondent Christina Milian, she said: "I love Christina. She is an amazing, undeniable talent. She is the real deal. She can really bring it when she sings and every time she steps on stage everybody is amazed.
"I worked with her years ago when she was a little kitten. We did the White House Christmas for Bill Clinton and it's just been neat to see her develop and mature over the years and watch her voice over the years."
Jewel went on to say that she is "excited" to be part of The Voice, saying that she and husband Ty Murray were big fans of the first season.
"I think what makes the show stand apart is these are really judges who know what they're talking about," she said. "They've been through it. It's fun to see them coach and cultivate and really mentor the talent, and not just critique them and tear them down."
The other guest mentors this season helping coaches Aguilera, Cee Lo Green, Blake Shelton and Adam Levine are: Lionel Richie, Miranda Lambert, Kelly Clarkson, Babyface, Ne-Yo, Robin Thicke and Alanis Morissette.
The Voice airs Mondays at 8/7c on NBC.
