Joe McElderry looked stunned as he was named the winner
ITV1's The X Factor was watched by more than 19 million people as Olly Murs and Joe McElderry fought for the title, according to the latest figures.
An average of 15.5m people tuned in to watch the full two-hour final on Sunday night.
But a peak audience of 19.1m, between 2115 and 2120 GMT, saw McElderry declared the overall victor.
The show accounted for 56% of the total TV audience. Sports Personality of the Year also attracted 4.7m to BBC One.
The teenager is set for the Christmas number one with his debut, The Climb
The annual awards ceremony, which saw Manchester United footballer Ryan Giggs take home the top prize, peaked with 6m viewers for the last 15 minutes of the show.
McElderry, from South Shields, had been the bookmakers' favourite to win the X Factor, and took nearly two thirds of the 10 million votes cast.
After clinching the title, he performed his single, The Climb, which was released digitally at midnight. A CD single will be on shop shelves from Wednesday.
On ITV2's companion show, The Xtra Factor, it was later revealed that McElderry had topped the phone vote for the last four weeks.
Speaking to GMTV on Monday, he said winning the show had been the "best experience" of his life.
"I am still pinching myself, I cannot believe it, that I am sitting here, and that I have just won X Factor," he said.
"I think it is going to take a long time to sink in. It was just amazing, it has been the best experience of my life."
The 15 million-strong audience is the highest for the reality singing contest - beating the previous peak of 15.02m, set on 15 November when rocker Jamie "Afro" Archer was voted out.
Lorraine Heggessey, head of production company Talkback Thames, said the ratings were "incredible for a show in its sixth series, proving that viewers appreciate the investment in the show and want programmes that become a big event".
Peter Fincham, ITV's director of television, called it "a great night for television".
The X Factor final is now the second most popular programme of 2009, after the final Britain's Got Talent, which attracted an average of 18.29m viewers for the whole show in May.
The X Factor's peak audience was 17.1m when examined in 15-minute chunks, as is customary for reporting audience figures. The 19.1m figure refers only to the five minute period when the announcement of the winner was made.
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