The 18-year-old told Wonderland that the child star label "always felt really odd" to her.
"I've just felt like I was an actor at 6 and 7 and, you know, a child who happened to act," she said. "But when you turn 18 you're seen as able to do more things and more roles."
Fanning also revealed that she knew from her first experiences of acting, such as in the movie I Am Sam, that she wanted to pursue a career in the business.
"For someone who's that young to feel completely at home being filmed playing someone else, that really means that that's where you belong," she said. "So that's how I view that film as a whole - as a moment when I just realised, 'I could do this. I could do this forever'."
Earlier this year, Fanning revealed that she has always felt "really secure" with herself.
> Dakota Fanning, Elizabeth Olsen for Very Good Girls
Watch a trailer for Dakota Fanning's upcoming movie Now Is Good below: