Filmmakers Scott Beck and Bryan Woods wrote the script for Haunt (2019) while they were also writing the screenplay for A Quiet Place (2018), without the expectation that either film would ever get made.
The interiors for the haunted house attraction were all sets built inside of a dairy factory.
Damian Maffei, who portrays the "Devil" character, also provided the voice for "Harper's Dad" in the flashback scene in the bedroom.
Justin Marxen, who plays the Clown, is a lifelong friend of filmmakers Scott Beck and Bryan Woods. He had to audition several times for the role as Beck and Woods had trouble separating their friend's jovial personality from the sadistic killer he wanted to play. After getting the role, he took inspiration from Javier Bardem in No Country for Old Men and Philip Seymour Hoffman in Mission: Impossible III.
The filmmakers visited various haunted house attractions in Kentucky.