The role marks Grammy-winner and American Idol alumnus Underwood's most prominent acting gig yet. She previously played a small role in 2011's Soul Surfer and has co-hosted the Country Music Association Awards for five years.
The live Sound of Music broadcast, which NBC announced Friday, will be produced by Craig Zadan and Neil Meron, the creative leaders behind TV's Broadway musical drama Smash as well as the upcoming Academy Awards telecast.
The Sound of Music debuted on Broadway in 1959 with film and theatre star Mary Martin as the convent novitiate-turned-governess Maria.
In 1965, a film adaptation saw Julie Andrews take on the role. It won best picture at the Academy Awards and has become one of her best-known performances.