The 28-year-old has a small role in Soul Surfer, a story about shark attack survivor Bethany Hamilton.
Speaking in Las Vegas on Monday, where she had just finished taping ACM Presents Girls Night Out: Superstar Women of Country, Carrie said: 'I'm happy with myself for the role and for the movie.
'Am I going to win an Oscar? No. It was so much fun and the important thing is getting the story out there.'
Underwood plays a youth pastor called Sarah Hill, a key figure in Bethany's life and recovery after the attack.
Hamilton lost her left arm at the age of 13 when a 14-foot tiger shark ripped it off while she was surfing in Hawaii.
According to Access Hollywood, she added: 'It didn't fit into my schedule at all, but we made time for it. It was so special. So if something else really special came along, I'm not going to say never.'