Initial filming started on May 13, 2018, in Fabijoniskes, a residential district in Vilnius, Lithuania, which was used to portray the Ukrainian city of Pripyat, since the district maintained an authentic Soviet atmosphere. At the end of March, production moved to Visaginas, Lithuania, to shoot both the exterior and interior of the Ignalina Nuclear Power Plant, a decommissioned nuclear power station that is sometimes referred to as "Chernobyl's sister" due to its visual resemblance and the nuclear reactor design used at both Chernobyl and Ignalina (RBMK nuclear power reactor).
Former Soviet General Nikolai Tarakanov (Ralph Ineson), gave several interviews about the series, which fascinated the Russian public upon its release. Tarakanov took issue with a few small details but otherwise praised the series and its depiction of the events, and stated he was portrayed accurately. Tarakanov, 85 in 2019, suffers from chronic disease related to radiation exposure from his time in Chernobyl.
Parallel to the show, after each episode's release, HBO released a podcast for each episode, "The Chernobyl Podcast," in which creator/writer Craig Mazin talks with Peter Sagal about many behind-the-scenes details about the writing and the production, and explained more about the history and real events behind the episode's storyline and the characters. Because of the series' underlying theme of lies, Mazin decided to do the podcast specifically to address discrepancies between historical fact and fiction, and which elements depicted were fictional and why.
Creator/writer Craig Mazin originally intended for the characters to speak with Russian accents, but quickly abandoned this idea after the interview process began, as the accents became a distraction for the actors.
To record a unique score for the show, composer Hildur Guðnadóttir went to the decommissioned power plant Ignalina in Lithuania, where a lot of the show was filmed, to record unique ambient sounds with the help of sound recording specialist Chris Watson and score producer Sam Slater. Then, back in the studio they listened to hours of recordings, sampling sounds from them. She composed most of the music for the show's soundtrack from those recordings.