The music matriarch had the deciding vote on Sunday night's sing off when it came to whether girl band Four of Diamonds or soloist Gifty would progress to the next stage of the competition.
She chose to send Gifty home, much to the shock of many viewers on social media.
Explaining that decision on Xtra Factor, Sharon, 64, said: "[I like both of these acts] very, very much. What I was going for was, 'Okay, out of these two, who do I think would make the best album?'
"If either one was there and they could win, which one could really crush it by making the album?
"And I just decided."
Gifty landed in the bottom three with Four of Diamonds and Ryan Lawrie following the Fright Night public vote. Ryan was saved (for the third time) by the lifeline vote, leaving Gifty and Four of Diamonds to sing for survival.
All the judges, bar Gifty's own mentor Simon Cowell, chose to save Four of Diamonds, who are mentored by Louis Walsh.
Afterwards, Simon publicly apologised to Gifty for getting the song choice wrong; he selected Fifth Harmony's 'In Love With A Monster' for Gifty, marking the second time she'd sung a Fifth Harmony song on the live shows.
"I'll tell you what happened, it was my mistake, Gifty," said Simon. "I should never have given you this song and you shouldn't be out of the competition at this point. It is not you, it's me."
Gifty, however, said: "Simon has been absolutely fantastic, he's always had my best interests at heart and has always done what made me feel comfortable. With him saying he picked the wrong song, I don't blame him, I feel he honestly felt it was the right song for me and I would smash it.
"I tried my absolute best. I knew it was a risk doing Fifth Harmony song, like third time. I personally feel people are going to think she's too predictable, but you know what, I did it and I have complete faith in Simon; he knows what he's doing."
She repeated that thought on ITV's Good Morning Britain on Monday, saying she felt the song choice was wrong but she had no regrets about her time on the show.
"Personally, I feel the song choice I had been given was a bit… I personally didn't feel too great doing it, another Fifth Harmony song, a third time. I honestly thought people would think, 'Oh, she's a bit too predictable.'"
"I had a chat with [Simon] after my performance on the Saturday and told him I was going home, I knew it," she added. "I didn't get a chance to speak to him on [Sunday] as he had to rush off.]
"Obviously I'm grateful for the opportunity and the fact he put me through as one of his final three girls and had faith in me. So many people auditioned for the show – thousands – and I made it to the final three years, and that's something to be proud of. I'm chuffed, I'm so happy.
"I was hoping to make it further, on the tour, and make a career out of it… but I won't let it hold me back, no. This is just the beginning. I will keep on singing and just milk it!"