The country superstar first auditioned for the reality singing competition in 2004 and became the show’s fourth winner.
And Underwood won’t be the only familiar face returning for Idol‘s fifteenth (and final) farewell.
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Other alumni appearing on the April 7 show will be Ruben Studdard, Fantasia, Taylor Hicks, Jordin Sparks, David Cook, Kris Allen, Lee DeWyze, Scotty McCreery, Candice Glover, Caleb Johnson, Nick Fradiani, Ace Young, Allison Iraheta, Amber Holcomb, Blake Lewis, Bo Bice, Brandon Rogers, Bucky Covington, Carly Smithson, Casey James, Chris Daughtry, Clark Beckham, Clay Aiken, Colton Dixon, Constantine Maroulis, Danny Gokey, Diana DeGarmo, Elliott Yamin, George Huff, James Durbin, Jessica Sanchez, Josh Gracin, Joshua Ledet, Justin Guarini, Katharine McPhee, Kellie Pickler, Kimberley Locke, Kree Harrison, LaToya London, Lauren Alaina, Melinda Doolittle, Pia Toscano, Sanjaya, Skylar Laine, Tamyra Gray and more.
Inaugural winner Kelly Clarkson pre-taped her finale performance because of the impending birth of her second child. The singer brought everyone – including herself – to tears in February when she performed “Piece by Piece” after guest-judging on the show for the first time.
“I’m pregnant and it’s nostalgic and I can’t believe it’s the last season,” the expectant mother said after singing. “Yeah, really sorry I just bawled.”
American Idol airs Thursdays (at 8 p.m. ET) on Fox. The two-part finale will air Wednesday, April 6 and Thursday, April 7.