Underwood won Season 4 of the singing competition show in 2005, and recently returned for Season 23 as a judge.

During Monday's episode of "American Idol," Carrie Underwood shared a heartfelt testimony after contestants went head-to-head during a performance of Brandon Lake's "Gratitude."

Carrie Underwood is giving fans a blast from the past in the most fabulous way. The country music superstar, 42, sent social media into overdrive after sharing never-before-seen throwback photos from the earliest days of her career—and the internet simply could not get enough.