The 20-year-old says her father sat her down two or three years ago and told her how much she had earned by starring in the Potter films. Up until that point she had been living on an allowance of just £50 ($80) a week.
Speaking to Britain's Vogue magazine, she says, "By the third or fourth film, the money was starting to get... serious. I had no idea. I felt sick, very emotional."
Emma added that she can finally be herself now that filming on the movie series has ended. The first thing she did when the final movie wrapped was to cut off her long hair.
"For the nine years I was on Harry Potter I was contractually obliged not to cut my hair, not to tan. All the normal things girls do, I couldn't," she says. "So when I got the chance to change my appearance, this is what I did."
Watch: Tom Felton's unhappy Harry Potter memories...