Zayn Malik shaved off all his hair because it was "a bit destroyed" after "bleaching it too many times".
"The bleach affects your hair doesn't it? So you've got to shave it off," he told Radio 1's Scott Mills.
He explained the radical new look as he launched his new single, Dusk Till Dawn.
The star also let slip there are some "sick people involved" with his new music, including Sia and Nicki Minaj.
The former One Direction singer said there are "plenty of people that I aspire to work with in the future".
"I was given some pretty big opportunities to work with some pretty cool people. I know there is a feature with Nicki Minaj, there's some other sick people involved. It's pretty cool.
"I didn't actually get to meet Sia in person," he also revealed.
"I wrote the song, someone played to her she did her thing. Hopefully in future I'll get to meet her."
Meanwhile, Scott has become one of just 36 people Zayn Malik follows on Instagram.
Zayn has nearly 24 million followers on Instagram but only followed 35, including girlfriend Gigi Hadid, until Friday afternoon.
Scott Mills is number 36 and says it's "made his weekend".