A stage musical based on the book was announced to be in development in March 2021, which was due to premiere in the UK in late 2021 or early 2022.

[1] In response to the announcement, Niffeneger revealed on Twitter she did not know about the project and then clarified that the theatrical rights belonged to Warner Bros.[2] The stage musical premiered at Storyhouse in Chester running from 30 September to 15 October 2022.

The cast included David Hunter as Henry with Joanna Woodward as Clare.

[3] On 8 February 2023, it was announced that the production will transfer to the Apollo Theatre in London's West End.

Dawes, Elchikhe, and Mahendran also returned as Henry's Dad, Charisse, and Gomez respectively.