In this study, we demonstrate that PFOS and perfluoroalkyl polymers can be efficiently decomposed to fluorine ions in aqueous solutions at room temperature and atmospheric pressure through the irradiation of incoherent visible LED light onto cadmium sulfide (CdS) and copper-doped CdS (Cu-CdS) nanocrystals (NCs). While visible light energy is typically insufficient to break the strong C-F bonds, we overcome this limitation by stepwise two-photon absorption processes, in which photogenerated transient species absorb an additional photon to produce a higher excited state. Semiconductor NCs exhibit high absorption coefficients and relatively long-lived excited states, facilitating the generation of multiple excited electrons. Under the circumstance, Auger recombination efficiently occurs, wherein the energy from the recombination of electron-hole pairs is transferred to another excited carrier to produce a higher excited state. Typically, electrons in the higher state tend to relax to the lowest excited state via nonradiative relaxation. However, a fraction of these electrons is either directly transferred to the PFAS when adsorbed onto the NC surface or is released into the medium, forming hydrated electrons. Hydrated electrons possess a reduction potential (-2.9 vs standard electron electrode (SHE)) exceeding that of metallic sodium, and therefore can be used to decompose PFAS through reduction reactions. In colloidal NC systems, trapping of a photogenerated hole by hole scavengers likely extends the lifetime of the conduction band electron (Fig. ), which facilitates the absorption of another photon to produce a negative trion (a three-carrier state composed of two electrons and a hole). Simultaneously, photoirradiation promotes the desorption of organic ligands from the NC surface, which in turn enhances the adsorption of PFAS onto the NC surface. Consequently, the efficient decomposition of PFAS occurs through cooperative multiphoton processes involving light-induced ligand displacements and Auger-induced electron injections via hydrated electrons and the higher excited states of NCs. This advanced decomposition technique can be applied to decompose other persistent chemicals under mild conditions, thus contributing to the realization of a sustainable fluorine-recycling society.