The 1987 movie adaptation of John Updike's novel starred Jack Nicholson as the Devil, and Cher, Michelle Pfeiffer and Susan Sarandon as three small town women who fall under his spell.
The 36-year-old, who was cast in March as Roxie Torcoletti on the ABC programme, said that there are slight differences between the show and the cinematic version.
She told Sci-Fi Wire: "I mean, this is really a different take. It's not just like the movie.
"I play Roxie, who's the same character as Cher from the movie. Huge shoes to fill, but honestly, getting to say that I play Cher, I feel like that's bragging rights there. It's more exciting to say I play Cher than to say I play a witch, which was already really exciting to say."
The X-Men actress added that her character will diverge by having a 15-year-old daughter, while she almost changed the colour of her part's hair in order to look more like the singing icon. She said: "I'm curly. I'm not dark, but I'm curly."
Romijn recently admitted that she nursed her twin daughters Charlie and Dolly on the set of the programme.
Eastwick will premiere on Wednesday, September 23 on ABC.