Based on the Naver webtoon of the same name by Kkomabi, it tells the story of a man who accidentally murders a serial killer, and a detective who pursues him relentlessly.

[23] Joel Keller of Decider wrote that "while A Killer Paradox seems like a pretty straightforward show, it should have a lot of tense moments", adding that it may have twists along the way.

David Opie of Radio Times rated it 3/5 and wrote that "tighter focus and keener sense of the message behind this conceit could have elevated the series more" but that "there's still tons of fun to be had when it comes to Killer's sheer ambition, not to mention the wish fulfilment of it all".

[26] Rhian Daly of NME rated it 4/5 and described the series as "far from a typical offering in the genre [that] adds flashes of other styles, like fantasy, into the mix" and "worlds apart from the usual murder and retribution fare", calling Choi Woo-shik, in particular, "phenomenal as the unlikely avenger".

[27] Pallavi Keswani of The Hindu wrote that "a product of smart writing, supported by some stellar performances, [it] emerges as slightly disturbing yet deeply intriguing watch".

[28] Melissa Camacho of Common Sense Media wrote that "overall, A Killer Paradox is an interesting thriller that requires close attention to fully understand what's happening".