The series Devil in Disguise: John Wayne Gacy was filmed mainly in Ontario, Canada , especially Toronto, Hamilton, and Kingston. It used those locations to stand in for 1970s Chicago and other Illinois settings.

Filming spots

  • Toronto : the main filming base, with New Toronto used for several scenes.
  • Hamilton : used for additional exterior and neighborhood scenes, including spots on King Southwest, Shadyside Avenue, and Franklin Road.
  • Kingston : included the Kingston Penitentiary and nearby streets for prison-related scenes.

Quick note

Production reportedly ran from September 2024 to February 2025.

Location| Use
---|---
Toronto| Main stand-in for Chicago 18
Hamilton| Extra urban and suburban scenes 1
Kingston| Prison and street scenes 1

TL;DR: it was mostly shot in Ontario, not Illinois, with Toronto doing most of the heavy lifting.