She was on-set shooting for an episode of "Oprah's Next Chapter," which will air Sunday, June 2 at 9 p.m. ET/8c on OWN, confirmed representatives from NBC and OWN.
The talk host and cable network's founder interviewed the NBC talent show's coaches Adam Levine, Blake Shelton, Shakira and Usher, as well as host Carson Daly and social media correspondent Christina Milian.
She also surprised the contenders with an unexpected meet and greet.
NBC gave Winfrey a tour of the set and exclusive access to the stars' trailers where she spent some time with the cast.
She picked an eventful day for her visit as the show was planning a tribute for the victims of the Oklahoma tornado, which included a performance by Shelton and his wife Miranda Lambert.
"The Voice" airs Mondays and Tuesdays at 8 p.m./7c on NBC.