Blue Birthday was produced by Playlist Studio, a Naver subsidiary known for hit web dramas targeting teens and young adults such as the A-Teen and Love Playlist series.

The director and writers reunited from previous mystery-ending web dramas The Best Ending (2019) and Ending Again (2020) to challenge new genres and materials with this fantasy romance thriller.

Kim Ye-rim and Yang Hong-seok were reported to be in talks for the lead roles on March 30, 2021, and were confirmed as protagonists after a script reading held in Seoul on April 5, 2021.

Lee Sang-jun joined the cast on May 14, 2021, followed by Kim Gyeol-yoo on May 25, 2021.

Principal photography wrapped in June 2021 after three months of filming, and behind-the-scenes stills were released on June 23.

A teaser video was released on June 10 to coincide with the birthday of the main character Ha-rin, meant to hint at the meaning behind the title 'Blue Birthday'.

The series ranked first among Korean content on Japan's AbemaTV platform and 7th among Korean content on Chinese streaming sites, with its Chinese fan page attracting about 3.58 million visitors.

A Japanese remake of the series, starring Shion Tsurubo and Airi Matsui, aired on Kansai Telecasting Corporation starting February 8, 2023, featuring the song 'Romance' by JO1 as its theme.