This research addresses the use of cyclodextrins (CDs) in aqueous solutions for the sequestration of fluorinated surfactants that generate environmental and health concerns due to their persistence and toxicity. Below their critical micellization concentration (CMC) in water, fluorinated surfactants can form inclusion complexes with CDs. CDâfluorosurfactant interactions above the CMC remain unexplored, and no structural information is available. To this end, we have analyzed small-angle neutron scattering (SANS) results to reveal the mode of CD association with ammonium perfluorooctanoate (PFOA) or ammonium undecafluoro-2-methyl-3-oxahexanoate (GenX) in water, and the structure and composition of mixed micelles formed by fluorinated surfactants and CDs. This fundamental information supports the design of CD-based adsorbent materials to selectively capture and remove per- and polyfluoroalkyl substances (PFAS) from aqueous media.