The series is based on the 2017 novel of the same name by Min Jin Lee, adapted for television by Soo Hugh, who served as showrunner, writer, and executive producer.

Apple Inc. acquired the rights to adapt the novel in August 2018, and the series received an official series order in April 2019.

Soo Hugh said it took six to seven months of worldwide searching to cast the main actors, and she required all actors, regardless of experience, to audition for their roles.

Filming began on October 26, 2020 across South Korea, Japan, and North America; Lee Min-ho finished shooting his Busan scenes in December 2020 before moving on to film in Vancouver, Canada, between February 6 and April 9, 2021.

The first season was produced in three languages: Korean, Japanese, and English.

Filming for the second season took place in Toronto from January 9 to March 27, 2023, followed by shooting in Japan from March 27 to June 16, 2023.

The opening theme song is 'Let's Live for Today' by The Grass Roots; creator Soo Hugh originally wanted to use 'Out of Time' by The Rolling Stones but could not secure the rights, so the title sequence was reshot several times with different songs before the final choice was made in post-production.

In February 2022, The New Yorker reported that novelist Min Jin Lee had been involved in the show's production at some point but was no longer involved, without the reason being disclosed.