The drama, which will premiere on The CW this fall, stars Britt Robertson as a young girl who discovers that she is a witch.
Dekker has now told the New York Post that he was attracted to the series because it is "such a well-written, smart show".
"I'm all about the duality of sensitivity and masculinity and this offered me a great chance to be masculine enough to be a love interest for two women, but sensitive enough to be a witch," he said. "Which isn't typically what we think of as a male vocation."
Dekker also revealed that he was "fixated on witchcraft" when he was younger, saying: "I was something of a dark kid, hypnotised by the occult. Plus, it's hard to grow up in the '90s and not have The Craft become one of your favourite movies!"
Robertson has previously revealed that she is "really excited" about taking part in the show.
Watch an extended trailer for The Secret Circle below: