It's official: Kris Allen is the new American Idol!

A record-setting 100 million votes determined the 23-year-old Conway, Arkansas native as the Season 8 winner tonight.

"The underdog, the dark horse, came back and wins the nation," Seacrest said after reading Allen's name.

A humble -- and shocked! -- Allen said: "Adam deserves this. I'm sorry, I don't even know what to feel right now. This is crazy!"

Look back on Idol's Top 13 contestants.

Allen wasn't considered a frontrunner going into the finale. Judge Simon Cowell declared his support for 27-year-old Adam Lambert, saying on Tuesday's show: "The whole idea about doing a show like this is that you hope you can find a worldwide star -- I genuinely believe with all my heart that we have found that with you."

But Allen, a business-school student, earned praise from the judges after his rendition of Kanye West's "Heartless" on last week's show.

Remember Season 8's Top 36?

"I had literally written you out of this competition," Cowell said then. "That, however, has all changed after that performance."

Carlos Santana, Cindy Lauper, Queen Latifah, Lionel Richie and the Black Eyed Peas were among the performers at the finale.

Familiar faces from the season also made cameos.

Nick Mitchell ripped off a hoodie and jeans to reveal the sparkly top and khaki shorts his character Norman Gentle donned during Hollywood Week.

Bikini Girl Katrina Darrell made an appearance -- showing off her famous swimsuit and noticeably bigger curves.

Joked Seacrest: "I'd ask what's new, but I already know!"

Darrell burst into song, and was joined by Kara DioGuardi in a surprise duet. At the end, DioGuardi stripped off her dress to reveal a bikini!

Later, Drama queen Tatiana Del Toro burst into song and was jokingly chased off by security before the show cut to commercial break.

Check out before and after photos of Idols who have lost and gained weight.

Tuesday night's Idol earned 23.8 million viewers, down from 2008's 27 million -- making it the lowest-rated finale in the show's history, according to the Hollywood Reporter.

See what an Idol stylist has to say about contestant fashion.

Prior Idols include Carrie Underwood, Kelly Clarkson and Oscar winner Jennifer Hudson.

Tell Us: Did Kris deserve to win?