<p>Tetracycline (TC) is one of the most widely used antibiotics in medicine and animal production, but its high solubility, aromatic structure, and resistance to biodegradation lead to its frequent detection in aquatic environments and pose serious ecological and health risks. In this work, Fe-doped WO₃ photocatalysts were successfully synthesized via impregnation of WO₃ with Fe³⁺ solution followed by thermal treatment. XRD and FTIR analyses confirmed that Fe³⁺ ions were successfully incorporated into the WO₃ lattice without forming secondary phases, accompanied by lattice distortion due to the close ionic radii of W⁶⁺ and Fe³⁺. Optical and electrochemical characterizations including DRS, PL, photocurrent response, and EIS measurements showed that Fe doping effectively narrowed the band gap from 2.56 eV (for pure WO₃ sample) to 2.34 eV (for 3.0Fe:WO₃ sample), inhibited electron–hole recombination, and enhanced carrier mobility. Photocatalytic tests under visible light irradiation showed that the 2.0Fe:WO₃ sample exhibited the highest TC degradation efficiency (46.8%), which was nearly double that of the pristine WO₃. Radical trapping experiments revealed that photogenerated holes (h⁺) and hydroxyl radicals (·OH) were the dominant active species, while the Fe³⁺/Fe²⁺ redox cycling played an important role in trapping e⁻ and continuously generating reactive ĚO₂^ě radicals. Furthermore, recycling experiments showed only a slight decrease in performance after five cycles. Finally, the photocatalytic degradation route of TC, including the formation of reactive intermediates, was proposed to better explain the underlying reaction mechanism.</p>