Carrie Underwood, Kelly Clarkson to Perform on 'American Idol' Finale

Show's two most successful winners will help tell it goodbye after 14 years

Carrie Underwood won 'American Idol' in 2005. Credit: Scott Legato/Getty Images

As the granddaddy of television's modern singing competitions, American Idol, prepares to crown the 15th and final Idol in its history, the show's two most successful discoveries, Carrie Underwood and Kelly Clarkson, return to help bid it goodbye.

The series' three-night grand finale is set to kick off Tuesday, April 5th on Fox, with a 90-minute retrospective special titled American Idol: American Dream, with current and former Idol judges (including original judges Simon Cowell, Paula Abdul and Randy Jackson), past contestants, host Ryan Seacrest and many of the show's behind-the-scenes team sharing personal memories, previously unrevealed stories and reflections on what the show has meant to them.

On Wednesday night, April 6th, the show's last-ever vote will take place as the remaining finalists battle it out live from L.A.'s Dolby Theatre, and on Thursday, April 7th at 8:00 p.m. ET live (tape-delayed PT), Underwood and Clarkson will both perform as part of the final episode. Also slated to return to the show are Scotty McCreery, Lauren Alaina, Kellie Pickler, Bucky Covington, Josh Gracin, Danny Gokey, and many of the other finalists and contestants from throughout the show's long run. The final episode will conclude with the crowning of the show's last-ever American Idol.

Kelly Clarkson, who was the first Idol winner in 2002, recently returned to the show to perform her Top Ten single, "Piece By Piece." Carrie Underwood, who is currently on her Storyteller Tour, was the show's season-four victor in 2005, and is ranked as the top-earning Idol contestant of all time. Country superstar Keith Urban has been an Idol judge since 2012.

The final episode of American Idol airs live, Thursday, April 7th, at 8:00 p.m. on Fox.