Raised in the farm town of Checotah, Oklahoma, she graduated in 2001 as salutatorian from Checotah High School. Underwood attended Northeastern State University, where she majored in mass communication and was a member of Sigma Sigma Sigma sorority.

Underwood's musical influences range from pop to country; she stated during Idol auditions that her favorite singer is Martina McBride. On the April 20 elimination show, Underwood demonstrated her ability to play the guitar. On the March 22 show, after a performance of Heart's "Alone", Simon Cowell said, "Carrie, you're not just the girl to beat, you're the person to beat. I will make a prediction, not only will you win this competition, but you will sell more records than any other previous 'Idol' winner!" He went onto say on the March 30 show that she has the "it" factor that will make her a star.

On May 25, 2005, she became the fourth winner of American Idol, beating Southern rocker Bo Bice, and she joins Kelly Clarkson and Clay Aiken as the only contestants who have never been one of the "bottom three" singers during any week's results.

As part of her title, Underwood gains a recording contract with Arista Records; her first single, "Inside Your Heaven," is scheduled for release on 14 June 2005. The B-side is "Independence Day," a cover of the Martina McBride hit.