The 31-year-old actor plays the serial killer in the new movie Extremely Wicked, Shockingly Evil and Vile.
Efron shared a still from the film Thursday on Instagram. The photo shows the actor portraying Bundy in what appears to be a courtroom scene.
"Ready for Sundance! #extremelywickedshockinglyevilandvile," he captioned the post.
Extremely Wicked will premiere at the Sundance Film Festival in January. The Sundance Institute shared another still of Efron and co-star Lilly Collins while announcing its lineup Wednesday.
Bundy was executed in 1989 after confessing to killing a number of girls and women in the 1970s. Extremely Wicked recounts his crimes through the eyes of his girlfriend Elizabeth Kloepfer (Collins), who struggled to accept Bundy was a killer.
Efron previously shared a photo of himself with Collins on set. The picture depicts the first meeting between Bundy and Kloepfer, who ultimately turned Bundy in to police.