Cillian Murphy is a fan of the film's original novel writer Claire Keegan. He remembers reading her novel "Foster" on a train and having to pull his hoodie over his face because he was crying.
Cillian Murphy pitched the film to Matt Damon during the production of Oppenheimer (2023). The film ended up being produced by him and Ben Affleck under their Artists Equity banner.
Cillian Murphy mentioned in an interview that the idea to cast Emily Watson as Sister Mary came to him in a dream, describing her as one of his favourite performers.
The film is dedicated to the women victims of the Magdalene Laundries, which ran from 1922 to 1998.
Much of the outdoor filming was done in the town of New Ross, Co Wexford.