AceShowbiz - Billie Eilish feared her hair would "burn" off when she dyed it blonde.

The 19-year-old star has opened up on changing her signature look and she admitted she's done so much to her locks over the years that she was worried about the impact of another style overhaul.

Appearing on "The Ellen DeGeneres Show" on Tuesday (11May21), she said, "I've been wanting it blonde for a while. I don't know what came over me. I saw a fan edit when I had green hair."

"It was like me, with whatever hair colour I had, and they just edited blonde hair on me and I was like, 'Ah! So sick! I want it!' "

"So I kind of thought of it as a dream. I didn't think it was going to happen because my hair has been through so much. I thought I would burn it all off if I tried, but I did it!"

The "Bad Guy" star also revealed it took her six weeks to go fully blonde, and had her first appointment back on 16 January (21).

Her hairstylist previously revealed that the makeover took six weeks.

"The process is real when you're doing it right. 6 weeks to get all the black of her ends without damaging it, along with her following my strict haircare regime. We actually loved all the stages of lifting the colour too but the end result is (fire emoji)."

While waiting for the process to complete, the Grammy-winning singer/songwriter hid her hair under a wig.

Before going blonde, she had black and neon green highlights.

Late last year, she revealed her plan to change her hair color ahead of the release of her documentary "Billie Eilish: The World's a Little Blurry".

"I'm changing it after the doc comes out," she told her online devotees. "It'll be the end of an era. I'm gonna give you a new era."