The widespread presence of metal ions poses significant environmental and health risks, necessitating highly sensitive and selective detection methods. Fluorescence spectroscopy is a powerful tool for trace metal detection, offering sensitivity, cost-effectiveness, and quick analysis with minimal sample preparations. This chapter summarizes the role of cyclodextrin (CD)-based fluorescent probes in metal ion detection, exploring their recognition performance and mechanisms. CD is utilized to develop fluorescent metal ion sensors, enhancing selectivity through its ability to form inclusion complexes. CD-modified fluorescent nanoparticles demonstrate excellent anti-interference properties, allowing for selective metal ion detection. The Chapter also highlights recent advancements in supramolecular structures, including CD dimers and polymers, and discusses the incorporation of lipophilic polymer dots (PDs) in nanomicelles with AIE properties. Most research focuses on ‘turn-off’ and ‘turn-on’ sensors, where emission intensity is influenced by mechanisms like Photoinduced Electron Transfer (PET), Förster Resonance Energy Transfer (FRET), Aggregation-Induced Emission (AIE), and intramolecular hydrogen transfer. These developments underscore the significance of CD-based fluorescent sensors in detecting metal ions.