The former supermarket worker chose to reprise her performance from the first live show, James Brown's 'It's A Man's Man's Man's World', in the hope that she could beat sing-off rival Cher Lloyd and her rendition of 'Everytime' by Britney Spears.
Following the showdown, both Louis Walsh and Cheryl Cole voted to save their respective acts, with Walsh stating that Byrne was "incredible... a real person living her dream", while the Girls Aloud star declared: "I backed [Lloyd] from the start and I will back her to the end."
Next, Dannii Minogue branded both acts as "great contestants" before explaining that she would send through the act "who has the vulnerability mixed with the confidence and who tugged on my heart strings", Cher Lloyd.
With the deciding vote falling to Simon Cowell, the music mogul announced that the decision was "straightforward", despite noting that he had supported Byrne "from the beginning" and thought that Lloyd's sing-off performance "was like hearing you for the first time".
After concluding his comments by saying, "I see one of you who can walk away from this competition with pride and a future," he opted to save Lloyd and ultimately eliminate Byrne from the programme.
The result decided, a gracious Byrne identified her favourite moment as recording a number one charity track in aid of Help For Heroes while her mentor Walsh, who is now the only judge without any remaining acts, thanked Irish viewers for their continued support.
One Direction, Rebecca Ferguson, Matt Cardle and Cher Lloyd will battle it out to become the winner of The X Factor in next Saturday's final at 7pm on ITV1.