Last night was also Cowell's final time on American Idol's judging panel and the show said farewell to him in several different ways, including a few video montages and a farewell message from comedian Ricky Gervais.
Former Idol judge Paula Abdul also appeared live to say goodbye to Cowell personally.
"The only reason they wanted me back here tonight is so that I could tell all of you the real reason why I really I left. But I don't think that's really what tonight is all about, is it? Although I will tell you this -- there's a baby backstage with Simon's haircut, and sweetheart, it's your turn to feed him," joked Abdul.
"Look Simon, my darling Simon, I've worked with a lot people over the years -- hot cheerleaders, big movie stars, world-famous recording artists, even a cartoon cat. But if I'm being truly honest, none of them hold a candle to you my friend. Our relationship on the show -- and I call it a partnership -- but it brought me immeasurable joy. I love all the fun we've had together, all the laughter we shared together. American Idol is not going to be the same without you, but as I only I can tell you, it will go on."
All of American Idol's previous winners except Cook then appeared on stage and sang Deltra Goodrem's "Together We Are One" to Cowell as the departing judge watched the tribute with Abdul sitting on his lap.
"I didn't think I was going to be this emotional, but I genuinely am. I just want to say -- it's great to have [Abdul] back -- but what Paula said is true: The show goes forward, it will be different," said Cowell.
"I just want to thank you from the bottom of my heart for the support, the fun, and your sense of humor. The truth is, when everyone asks who's going to replace me, who's going to be the next judge, the truth is you guys are the judge of this show. You've done an incredible job over the years."
In addition, comedian Dane Cook performed a song based on Cowell insults before several former American Idol audition rejects appeared on stage to sing back up. One of them, Ian Benardo, subsequently grabbed the mic and shouted, "I'm going to replace you Simon Cowell!" -- causing Fox to cut to commercial.
All of American Idol's Top 12 ninth-season finalists performed during the finale, introducing "School's Out" for Alice Cooper as Orianthi accompanied him on guitar and "Again" for Janet Jackson.
The 127-minute filler-filled broadcast also included the ninth season's final Ford music video; video montages of Dewyze and Bowersox's American Idol journeys; live updates with Bowersox backers in Toledo and Dewyze fans in Mount Prospect; third-place finisher James performing with former Poison frontman and recent The Celebrity Apprentice winner Bret Michaels; fourth-place finisher Lynche performing with Michael McDonald; sixth-place finisher Magnus and fifth-place finisher Kelly performing with the Bee Gees; and Bowersox and Dewyze singing with Joe Cocker.
Viewers also saw Allen perform "The Truth:" Dewyze and Bowersox each receive a new Ford Fiesta; Dewyze perform with Chicago; Bowersox perform with Alanis Morissette; Aguilera sing "You Lost Me;" Jackson sing "Nasty Boys;" Hall & Oates perform "You Make My Dreams;" General Larry Platt perform "Pants on the Ground" with William Hung; and Underwood perform "Undo It," which she co-wrote with DioGuardi.
The finale broadcast concluded with Dewyze singing U2's "Beautiful Day," which will serve as his first single.