“American Idol” judge Carrie Underwood surprised viewers Sunday with a callback to her time on the show in 2005.

American Idol' judge Carrie Underwood had fans in shock when she performed Heart's "Alone" on the show for the first time ...

If 'American Idol' finalist Mattie Pruitt wants to stick around she may want to consider Carrie Underwood's advice.

There were enough hints dropped by American Idol regarding this nostalgic performance, but still, it took fans by surprise.

Tonight on American Idol, the Top 12 recreate iconic moments from the singing competition's past as Season 3 winner Fantasia ...