But the former redhead, who has dyed her eyebrows dark brown to match her new tresses, looked barely recognisable as she was spotted out and about in Cambridge.
With a bright orange hat pulled down to conceal her new look, we can't help wondering if the model student is missing her fiery mane as much as we are.
Lily confessed recently that she was teased as a child for having red hair: "When I was younger I definitely did face anti-ginger prejudice. As a child all teasing hurts, whether it's because you're fat or a different race or have red hair."
Lily, who is studying History of Art has reluctantly left her American boyfriend behind to return for her third year at Cambridge University.
But while Lily is clearly browned off with being a redhead, Nicola Roberts can't get enough of it. The Girls Aloud star was spotted out in London this week with nearly neon orange hair extensions.
Thinking of going for a colour change like Lily? Check out our beginner's guide to hair colour.
Redhead v brunette: What do you think of Lily's new look?