Stewart said that Theron immediately put her at ease when they first met prior to the filming of their new fairytale epic.
"She's awesome, she's a nut bag! My favourite people in the world are the ones where you're like, 'Wow, you are crazy, I love you'," she recalled, reports Flicks and Bits.
"I was really intimidated by the idea of this all. I was thinking, 'Oh God, Charlize, she's stunning, she always makes bold choices, she's got it all - literally'. But then when you meet her, it's so not off-putting."
Stewart continued: "Her energy is so in your face as well, it's just motivating. It just makes you want to push back, and I love people like that."
The actress went on to suggest that Theron was "perfect" casting for Snow White and the Huntsman's White Queen.
"[Theron's] got this presence, and people say that about a lot of people, but she can level you in a great way, in a bad way, however she wants," Stewart explained.
Stewart recently revealed that she's hoping to play the "psychopathic, evil c**t" Cathy Ames in a new big-screen version of East of Eden.
Snow White and the Huntsman opens in cinemas on June 1 in the US and the UK.
Watch a trailer for Snow White and the Huntsman below: