Cheryl Cole finally landed her longed-for role as a judge on the US version of The X Factor today and declared: "I can't wait to get started."
But the 27-year-old's new job means she will leave the British version of the show after three years.
Today's announcement by Simon Cowell and bosses of the Fox network ends months of speculation about whether Cole could make it in the US.
Launching the show with Cowell could make the erstwhile Girls Aloud singer a huge star, but there had been fears her accent could be impenetrable for American viewers.
Cole will take her place on the panel alongside show boss Cowell, respected former record boss LA Reid and one more unnamed figure when the show starts later this year.
Cowell has long championed her for the show but it is a high-risk gamble because she is a virtual unknown on the other side of the Atlantic.
He said: "I'm thrilled for Cheryl. She is massively excited about this show, and has been fantastic to work with.
"She is also a complete brat. Most importantly, this girl can spot talent."
But the appointment spells the end of her run on ITV's hugely successful Saturday night UK show. She has twice mentored the eventual winner during her stint.
ITV's official X Factor website confirmed she would be quitting the programme. It said: "It's with a pride-filled lump in our throat that today we announce Cheryl Cole's departure from the UK version of The X Factor."
A spokesman for ITV said the line-up of judges would be announced "in due course".
Cole said: "I'm so excited to be taking part in the American version of The X Factor.
"I absolutely love it here in the UK, and with the talent they have out in America, I'm sure we're going to find someone very special.
"I can't wait to get started. I just can't decide whether I am more excited to find and nurture the talent or for the unbelievable amount of amusement and entertainment I will have watching Simon doing everything and anything he can to beat me.
"He's tried to beat me for three years in the UK, and hasn't even come close. His ego must be so bruised. America is gonna love this."
Just last week Cowell had publicly thrown his weight behind the Fight For This Love singer Cole.
And he said that bosses at Fox had been impressed by her from the early stages of negotiations to launch a version of the show.
Cole, who divorced footballer husband Ashley Cole last year, has spent increasing amounts of time in the US in recent months in preparation for the move.
She is well placed to lend her expertise after famously finding success through an appearance on another TV talent show. She entered Popstars: The Rivals - a forerunner of The X Factor - which assembled her group Girls Aloud.
Executive producer of the new show, Cecile Frot-Coutaz, said: "As a young artist whose talent show discovery led to almost immediate stardom, Cheryl's career exemplifies the promise of The X Factor.
"Her empathy and passion for identifying and nurturing undiscovered talent has made her a huge hit with British audiences, and I have no doubt America will fall in love with her beauty, her accent and her incredible chemistry with Simon Cowell."
Auditions for the US series have already begun.
The new show will give music wannabes a chance to win a recording contract with Sony and Cowell's company Syco said to be worth £3 million.
Cowell - now worth £200 million according to the Sunday Times Rich List 2011 - found fame as a judge on American Idol, but announced last year he was leaving to launch a version of The X Factor.
But he and Cole's involvement in the new show could have a huge impact on the original X Factor.
ITV's programme chief Peter Fincham has already said that Cowell will no longer have a weekly role on the series he created and led.
Piers Morgan was among those who offered their congratulations to Cole today.
In a message posted online he said: "Congrats to my friend Cheryl Cole on landing US X Factor judging gig. Am available for elocution lessons whenever you like."
Mike Darnell, president of alternative entertainment for the Fox Broadcasting Company, welcomed Cole's appointment.
"Cheryl Cole has the whole The X Factor package - she's an incredibly talented artist and performer, as well as a style icon, and she has that special charisma that draws in fans around the world.
"Cheryl's charm and chemistry with Simon have been a key part of the overwhelming success of The X Factor in the UK, and we can't wait to welcome her to the US on our air."Reuse content