The actor told TV Choice that the success of his CBS drama - which also stars Jim Caviezel - is partly down to its themes of vigilantism.
"It promises and delivers thrills and puzzles, which are two things people like," he explained. "You also have to be aware that American audiences have a hunger for avengers, I guess - the vigilante, the lone operators that will cut through the red tape and set things right.
"That's such a strong theme in the States, and it's part of what we are delivering. It goes back to cowboy movies and everything like that."
Person of Interest - which debuts on Channel 5 in the UK on Tuesday, August 14 - stars Caviezel and Emerson as two men who operate outside the law, preventing crimes before they happen with the aid of a futuristic surveillance device.
"I know the creator of the show Jonathan Nolan always says that London was his inspiration for this notion of a permanent overlapping surveillance system, because anywhere you look from just about any place in town, you can be seen by some camera or other," Emerson explained.
"Now since we shoot on the streets of New York all the time, you don't have to look far to see a vantage point from which we could be watched electronically. It's striking."
Person of Interest returns to CBS in the US for a second season on September 27.
> Lost stars to reunite on Person of Interest
> Person of Interest to air on Channel 5 in the UK
Watch a Channel 5 promo for Person of Interest below: