Apart from some establishing shots of New York at the beginning, the film was mostly shot in London, England with the old Lambeth Hospital being used as the police station and jail.
According to the book 'Bronson's Loose' by Paul Talbot, the original working title "Death Wish III" was changed to "Death Wish 3" because The Cannon Group, Inc. conducted a survey and found that nearly half of the U.S. population could not read Roman numerals.
Alex Winter recalled filming a scene where Charles Bronson hits him with a lead pipe took longer than anticipated because Bronson didn't show up to do so. After a while, Michael Winner said, "Charlie, we all want to go home, would you please hit this man so we can go home?" Bronson replied, "I can't hit this kid, he looks like a fucking choirboy. I'll lose my audience".
Charles Bronson uses a Wildey .475 Magnum hand cannon in this movie. It was his personal handgun in real life, and he suggested it as a means to make the film unique. In a 2005 interview in 'American Handgunner' magazine with Wildey Moore, the gun's creator and a technical consultant to the production, Moore said that sales for the weapon increase each time this film is aired on cable television. Moore said: "To this day there is a spike in Wildey Magnum sales every time 'Death Wish 3' appears on cable TV."
As principal photography was mostly filmed in London, the movie featured extras and background artists playing a variety of characters including police officers and gang members. Their audible dialogue was in various English accents. This movie was set in New York City, and required American accents. As such, during post-production, director Michael Winner enlisted the assistance of the military personnel of the U.S. Air Force stationed in England to dub over the various English accents.