The Bad Neighbours star admitted he had some 'reservations' about the role, but said this one was particularly 'intriguing' to him.
"Initially, I had reservations about playing a serial killer," he told Variety.
"I've seen people make horror films like this before, and it seems like an aggressive play to separate yourself from a perceived image."
Efron, 31, said he'd already seen too much 'killing, hacking and slashing' in scary movies, which is why the psychological aspect of the film appealed to him.
He added: "This movie was really about a human being, somebody that perhaps I would have been friends with. And a love story from a very unique perspective.
"I've never seen that before. It's intriguing to me. I think it's more psychological and even more kind of a mindfuck."
The film, which premiered at the Sundance Film Festival last weekend, has faced criticism from people who believe it 'romanticises' Bundy by using a 'heartthrob' like Efron in the role.
One person tweeted: "Can we not sexualise Ted Bundy? He raped, murdered, and decapitated women and had sex with their dead bodies. Not here for this hyper-sexualised Zac Efron film."
Another wrote: "Friendly reminder that Ted Bundy is a disgusting MONSTER who has killed, kidnapped and raped over 30 people. Please stop romanticising him/calling him attractive because of the Netflix documentary and his biopic with Zac Efron. He is, and always will be, ugly inside and out."
However, others have pointed out that Bundy was described by many as being 'charming and good looking', traits he used to lure many of his victims.
"The most exciting thing for me was being able to sort of lend that Ted Bundy charisma to the part," Efron explained to E! News.
"I hope that comes across the most."
The release of the film coincides with the 30th anniversary of Bundy's execution, following the brutal rape and murder of at least 30 women and girls.
Efron said director Joe Berlinger was an 'amazing source' of knowledge for researching the role - especially as the filmmaker also produced the recent true crime documentary Conversations with a Killer: The Ted Bundy Tapes, which was released on Netflix at the beginning of this year.
Featured Image Credit: Voltage Pictures