The 32-year-old singer lost out after finding herself in the bottom two with Rylan Clark, following the first public vote of the series.
Both singers performed again in a bid to remain in the competition, Rylan singing the Dreamgirls song One Night Only, and Carolynne delivering a passionate performance of Faith Hill’s There You’ll Be.
And while Nicole and Gary both went with their acts, Tulisa voted to save Carolynne, saying, “I have to base it on that performance being a singing competition, it hurts me to say it but I have to send home Rylan.”
Gary, meanwhile, told Carolynne, “Thank God you got to sing like that, it makes it easy for all the judges.”
Eventually, Louis was left with the casting vote – but he appeared to agonise over his decision while being urged by both Dermot and Gary to make up his mind.
And despite initially saying, “I want to save Carolynne,” he ultimately chose to take the vote to deadlock – a decision which proved heartbreaking for the singer after she was revealed to have polled fewer public votes than Rylan.
And as the crowd booed the decision, a furious Gary Barlow stormed off set – later returning to blast Louis for his decision.
“That was a joke, an absolute joke,” he fumed. “Two years now and you’ve lost out to joke acts.”
Louis later justified his decision by saying, “I wanted to see who got the least amount of votes, it’s a very tough one.”
Carolynne, meanwhile, said on the show she was “pleased for Rylan,” adding that “he had had a hard time”.
However she admitted afterwards she was “gutted” to be leaving the show so soon, but took the opportunity to take a potshot at Louis, admitting, “He never saves me” – in reference to him rejecting her at the judges’ houses stage in 2011.
Meanwhile the eleven other acts, including favourites Ella Henderson and Jahmene Douglas, all sailed through to next weekend’s show which will have the theme of love and heartbreak.