A news release says the former "American Idol" champion and Grammy-winning country star will play Maria von Trapp in a live performance based on the musical. It will air around the holidays in 2013.
The role is Underwood's most significant work as an actress yet. She played a small part in the 2011 film "Soul Surfer" and has served as co-host of the Country Music Association Awards for five years.
In von Trapp, she's tackling a beloved character whose popularity has endured for decades. The Rodgers & Hammerstein musical debuted on Broadway in 1959 and the 1965 film starring Julie Andrews won the best picture Academy Award.