The project is directed by Sean McNamara and tells the true story of teen surfing champion Bethany Hamilton, who lost her arm in a shark attack at the age of 13.
According to Variety, Underwood will play a church youth leader. She follows the path to the big screen braved by such "American Idol" veterans as Kevin Covais ("College"), Katharine McPhee and, of course, Oscar winner Jennifer Hudson.
"Soul Surfer" is produced through Mandalay Vision and Brookwell McNamara Entertainment and Life's a Beach Entertainment. It has distribution through the Sony-affiliated Affirm Films.
Underwood, one of the biggest names in country and popular music, had her own FOX holiday special in December and will make her acting debut in an upcoming episode of "How I Met Your Mother" on CBS.