The drama will follow Cassie (Britt Robertson), a young girl who moves to Salem and discovers that she is a witch.
In a recent Twitter post, former Buffy and Angel star Carpenter admitted that she is disappointed not to be part of the project.
"Sad because Secret Circle pilot I was hoping to test for was a role offered to someone else," she explained. "I really was hoping to be a part of that show."
The actress has recently appeared in episodes of Greek, Legend of the Seeker and CSI. She also starred in 2010 action film The Expendables.
Natasha Henstridge, Louis Hunter, Thomas Dekker, Phoebe Tonkin, Gale Harold, Shelley Hennig and Jessica Parker Kennedy have all signed up to star in Secret Circle.
The pilot will be executive produced by The Vampire Diaries showrunner Kevin Williamson.
> Check out Digital Spy's pick of this year's pilots