The actress signed on last month to appear in the forthcoming sci-fi film, which will be helmed by Rupert Wyatt (Rise of the Planet of the Apes).
Talking to MTV News, Theron joked that she "stalked" Wyatt in order to be part of the project once she heard its initial pitch.
"It's a pitch that I heard a month or so ago and I fell in love with this pitch," the Snow White and the Huntsman star recalled.
"And ironically, at the same time, I really wanted to have a general [meeting] - 'cause you know how I stalk directors - with Rupert 'cause I really love what he's been doing.
"I brought up the pitch to him and he said, 'I really love this. I think we should talk about it'. And so it was really just the universe coming together."
Theron went on to reveal that she is still uncertain which role she will portray in Agent 13, which is an adaptation of the 1988 comic centring on survivors of a lost civilization called Lemuria.
"You know, we're writing it right now so it's a very, very loose pitch, but it's an alternate world story so it's big and epic and cool," she said.
> 'Snow White' Kristen Stewart: 'Charlize Theron is loveably crazy'
Watch Charlize Theron in the trailer for Snow White and the Huntsman below: