Mega Man alumn and Mighty No. 9 creator Keiji Inafune (who had joined Level-5 following its acquisition of his company Comcept in 2017) originally served as the producer for Fantasy Life i: The Girl Who Steals Time. However, following "harsh" feedback from internal playtests, Inafune left the company in 2024, forcing Level-5 CEO Akihiro Hino to take over as producer. This led to a major overhaul of the game, as open-world exploration, parkour, cross-play, and cross-save functionalities were added, as well as refinements to the UI, story, and progression systems.

Laura's Strangeling form, the Free-Spirited Cap, is based on the cap she wears while disguised as a boy in the original Fantasy Life.