In this study, carbon dots (CD)-embedded film was successfully fabricated for Fe 3+ sensing via a one-pot process. The carbon dots for Fe 3+ ion detection were synthesized using the cellulose/ionic liquid solution for different treatment times. With the increase of the treatment time, the N-doped graphitic structure in the core and the functional groups on the surface were highly developed in the carbon dots. The properties and structures of the carbon dots were characterized using TEM, UV–Vis spectroscopy, XPS, IR, TCSPC, and PL spectroscopy. The carbon dots prepared by 12 h treatment showed a high quantum yield of 28.4%, and the superior stability for long-term storage, UV exposure, ionic strength, and pH change. The carbon dots in the film, as well as in the aqueous dispersion, revealed highly selective detection toward Fe 3+ . The CD-embedded cellulose film can be used as a Fe 3+ indicating film with good reusability, outstanding transparency, and high photostability. Graphic abstract