The singer-songwriter performed Ed Sheeran's Lego House in her final sing-off (see performance below), while Hannah took on Miley Cyrus's recent hit Wrecking Ball.
But her dazzling performance, which Gary Barlow referred to as "touched", wasn’t enough to send her through to the talent show's next week.
After praising the 19-year-old, former Take That star Gary said: "I'm just confused I don't know how these two singers are in the bottom two.
"But I do have to choose, the act I'm sending home is Abi."
Sharon Osbourne said that Abi’s passionate performance was too late to save her. She said: "It's so frustrating because now you deliver," and opted to send her home.
Nicole Scherzinger, who found herself in a tricky situation as she was mentor to the two singers in the sing-off, abstained from the vote. "I refuse to choose between my girls," she said.
The result means that Nicole has lost the first act from her Girls category.
Speaking to X Factor host Dermot O'Leary, Abi said: "I never in a million and one years anticipated that I would get this far. I've had the time of my life and I've met the most amazing people. I would never change it so thank you."
She added on The Xtra Factor: "Obviously I'm gutted but I'm so thankful for this experience. I can't put it into words. It's been amazing."
The latest live results show of the year saw magnificent live performances from Celine Dion and Robbie Williams, while Gary Barlow and Miley Cyrus will take the X Factor stage on next Sunday's results show.
What do you think? Should Abi have been voted off?