The 18-year-old, who failed to get past bootcamp on last year's show, was seen performing to Prince's Purple Rain.
Speaking backstage with her nan - who Chelsea calls her inspiration - the teenager admitted: "I’m scared of getting buzzed."
On stage, Chelsea reveals to the judges: "At the moment the I do admin office work for my dad but I’d really like to be a worldwide singer."
Bursting into a performance of Purple Rain by Prince, will the X Factor judges regret their mistake?
Alesha raved: "I can see how much this means to you. This is an emotional experience, you're different. I love how shy and sweet you are then this powerful voice comes out."
David added: "You're beautiful girl with a great personalty. you could be a superstar."
Simon told the teenager: "When I heard you were young to sing Purple Rain, I thought it was a risk, but you've got something quite distinct in your voice. You sound like a pop star and look like a pop star."
With four yeses, it was through to the next round for Chelsea.
"Hopefully next time she'll have some confidence," David said after Chelsea had left the stage.
Simon quipped: "Now I've said yes, she'll have come confidence."
Watch [tag]Chelsea Redfern[/tag] on Britain's Got Talent below...