The drama, which was officially picked up by The CW last week, focuses on a young girl called Cassie who discovers that she is a witch.
Speaking to TV Guide, Robertson admitted that she didn't want to assume that the project would go to series.
"It's like, no matter how much buzz, you're always crossing your fingers and hoping for the best," she explained. "I'm really excited to be a part of it and I'm super glad that it's actually happening and we're going to start shooting soon. It's all exciting."
Robertson also dropped some hints about what viewers can expect from the show, saying: "The coolest thing about the show to me when I first read it was that my character Cassie is this normal, average, teenage girl living her life, whatever, and then she gets thrown into these crazy circumstances and it's one after another, it's a snowball effect. She's sort of uncovering this new world along with the audience. It's an exciting thing. Also, there's the supernatural element, so that's kind of fun."
She added: "The big thing is just like, 'What's going on?' I think as soon as [viewers] see the first episode, they're going to know what's happening in the show and what's going to happen with these characters."
The Secret Circle, which will be paired with The Vampire Diaries, will premiere in the fall.
Watch a trailer for Secret Circle below: