The former Lizzie McGuire star looked beautiful as she arrived to film an interview at the Good Morning America studios on Monday, 30 March.
We're still doing a double take when we see that hair!
Hilary shocked us all earlier this month when she switched her trademark golden blonde for this bright aquamarine hue… and now we know why!
Appearing on The Ellen DeGeneres Show this week, she said: "I have never done anything like this. I was in Cabo with my son and I was staring at the ocean and said, 'I want that on my head. And it happened!'"
As for three-year-old Luca, it must have been quite a shock for him to see his mum sporting green hair, right?!
Well, apparently he loves it!
"Luca is very particular about how he likes my hair. No buns. If I have a ponytail he's like, 'No, hair down mum, please.' At least he knows what he likes. He saw it and said, 'Wow'."