But the singer revealed on Twitter that the new strawberry blonde shade was not her intended colour: "So I didn't get to the exact color I wanted from being black for so long! 2get to goal I have 2b GINGER for 3WKS"
Another tweet explained: 'If I don't wait 3wks, I'll end up w/no hair or a #pixie90scutw/abarretteinthefront It's okay, I'll get to my secret color(s) soon! #patience."
With any dramatic colour change, it's always best to do this in stages to ensure the least amount of damage and stress to hair - so Katy's clearly doing the right thing.
We actually think this temporary shade suits her - and of course is a hot trend with other A-listers including Emma Stone, Blake Lively and Drew Barrymore.
But we can't wait to see her final 'secret' shade!