The X Factor presenter Olly Murs said he was a "plonker" after he told a contestant she was going home before the result was officially announced.
After Murs and his co-host Caroline Flack asked the judges to choose who they wanted to send home between Monica Michael and Anton Stephans, Murs told Michael she was eliminated, before Flack said: "No, Olly, she's not."
Murs then said: "Sorry. I apologise for that. Sorry Monica. I do apologise."
It appeared Murs thought three out of the four judges had opted to send Michael home, meaning that she would have been automatically out of the competition but, as two judges had voted for each contestant, the "deadlock" was decided by the public vote.
Flack then announced: "The act who received the fewest votes from the public and who will be leaving the competition tonight is ...it's Monica Michael."
After the show, Murs tweeted: "I apologise to everyone tonight I made a massive f%#k up at the end. It was so tense!! I'm still learning & hope that never happens again!"
Former X Factor host Dermot O'Leary tweeted support, saying: "Didn't see the show tonight,but live TV is a tricky old beast at times. After this weekend... perhaps some sense of context should prevail."
Murs then replied: "Cheers Derm!! Beating myself up about it mate! What a plonker!"
After the show Flack tweeted: "We all make mistakes . I make LOADS in life and on telly ... It's live."
An X Factor spokesman said: "As Olly said himself on Twitter, it was a genuine mistake."
Murs' mistake in the results show comes after Judges' Houses went live for the first time in the show's 11-year history last month - proving to be a ratings turn-off for viewers.
It was criticised due to sound issues in that the judges could not always hear what they were being asked by the presenters.
Michael's dreams were not the only ones to be shattered, as Max Stone was also voted off the show.
It was a double blow for the pair who were also told they will not be included in The X Factor live tour.
Londoner Michael was originally supposed to perform (Bang Bang) My Baby Shot Me Down by Nancy Sinatra on Saturday night's show - but her song was changed at short notice following the attacks in Paris.
Flack told the crowd. ''There are a couple of song choices in tonight's show that both the judges and contestants felt we should change.''
Her rendition of Veronika Bozeman's What Is Love was praised by the judges.
On learning of her fate on the Sunday results programme, 26-year-old Michael said: "Oh my God I had such an amazing journey."
Devon-born Stone received the fewest public votes for his version of Secret Garden by Bruce Springsteen from the movie Jerry Maguire.
On Saturday night's show, Cowell made reference to the Paris attacks, saying: ''In light of what happened last night, we would like to send our thoughts and our prayers to everyone who was affected in Paris last night. And most importantly, please stay safe."