For her performance in Little Girl Blue, Marion Cotillard became the first actress to be nominated for a César Award for Best Actress for a documentary film.
Carole Achache was one of four real-life characters that Marion Cotillard portrayed in 2023. The others were Cleopatra in Astérix & Obélix: L'Empire du Milieu (2023), Louise of Savoy in Léo, la fabuleuse histoire de Léonard de Vinci (2023), and Solange d'Ayen in Lee Miller (2023).
The film was shot in chronological order. This is only the second film starring Marion Cotillard to be shot in chronological order, the first was Deux jours, une nuit (2014).
Marion Cotillard filmed all of her scenes in 8 days after spending only two months preparing for the film.
The film is based on the life of French writer and photographer Carole Achache, the mother of director Mona Achache. Carole did a similar thing when she wrote the 2011 book "Fille de" ("Daughter of"), about her relationship with her mother, the novelist and screenwriter Monique Lange.