Billie Eilish Didn't Think Her Blonde Look Would Be Possible: 'My Hair Has Been Through So Much'

Billie Eilish is explaining what led to her latest hair revamp.

Making a surprise appearance on The Ellen DeGeneres Show Tuesday, the "Bad Guy" singer, 19, talked her new look, including why she decided to go blonde. Eilish revealed her new hair transformation to the world in March, after previously experimenting with neons, pastels, and even two-toned looks like her signature black and green.

"I've been wanting blonde for a while, I don't know what came over me," she said. "I saw a fan-edit when I had green hair, it was me with whatever color hair I had, and they edited blonde hair on me and I was like 'Ah! So sick, I want it!' "

"I thought of it as a dream," the Grammy winner added. "I didn't think it was going to happen because my hair has been through so much. I thought I would burn it off if I tried. But I did it!"

Eilish explained that the transition from dark to light hair was "very hard" and happened over about six weeks, starting on Jan. 16. "It took a long time," she said of the process.

RELATED: Billie Eilish Debuts New Look for British Vogue: 'It's All About What Makes You Feel Good'

Michael Rozman/Warner Bros. Billie Eilish

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For the cover of British Vogue's June 2021 issue, unveiled earlier this month, Eilish wore a series of vintage-inspired outfits in the bold photoshoot. In one image, she wears a custom trench coat and corset by Burberry, while also showing off a tattoo she got last year, which she previously told fans they'd never see.

Other photos show the Grammy winner wearing a custom catsuit and corset by Mugler, as well as a corset dress from Alexander McQueen paired with latex gloves, suspender belt and stockings from Atsuko Kudo.

"My thing is that I can do whatever I want," she told the magazine. "It's all about what makes you feel good. If you want to get surgery, go get surgery. If you want to wear a dress that somebody thinks that you look too big wearing, f--- it — if you feel like you look good, you look good."