The Footloose actress won a small role as a Hogwarts student in Harry Potter and the Philosopher's Stone, and developed a crush on lead actor Radcliffe.
The then 11-year-old actress sent Radcliffe a love note and a Beanie Baby on Valentine's Day to profess her crush.
In an interview on Live! with Kelly, Hough said: "[I] never heard back. And now I'm really embarrassed. I see him sometimes, around, and I just turn the other way and walk away. I'm too nervous [to reintroduce myself]."
Hough is now dating TV host Ryan Seacrest.
The 24-year-old is in line to star in Safe Haven opposite Josh Duhamel. She will next be seen in Rock of Ages with Tom Cruise, Catherine Zeta Jones, Diego Boneta, Russell Brand and Alec Baldwin.
Watch a trailer for Rock of Ages below: