<p>Enhancing the visible light response activity of semiconductor photocatalytic materials is a core challenge in the field of environmental catalysis. Transition metal doping has become an effective modification strategy due to its tunable electronic structure characteristics. In this study, aiming at the problems of high carrier recombination rate and insufficient visible light response of Bi₂WO₆ photocatalyst, a Fe³⁺ doping modification strategy was proposed. Fe³⁺-doped Bi₂WO₆ (Fe³⁺-Bi₂WO₆) was synthesized by hydrothermal-calcination method, and its visible light photocatalytic degradation performance for tetracycline (TC) was systematically evaluated. Based on the ion radius matching characteristics of Fe³⁺ (0.0645&#xa0;nm) and W⁶⁺ (0.060&#xa0;nm), Fe³⁺ directionally replaces the W⁶⁺ site in the Bi₂WO₆ lattice and induces the formation of oxygen vacancies. The characterization results show that the specific surface area of Fe³⁺-Bi₂WO₆ is increased to 29.82 m²/g (the original phase is 24.00 m²/g). The response range of its absorption spectrum in the visible region has been significantly expanded (the band gap is reduced from 2.90&#xa0;eV to 2.58&#xa0;eV), and the photocurrent density reaches 0.835 × 10^− 3 mA/cm² (the original phase is 0.356 × 10^− 3 mA/cm²). When the doping ratio was optimized (Fe³⁺: Bi₂WO₆ = 0.26:100), the degradation rate of TC reached 85.97% within 60&#xa0;min, and the reaction rate constant (0.03027&#xa0;min⁻¹) was 1.53 times higher than that of the original phase. The mechanism investigation reveals that the abundance of oxygen vacancies not only significantly enhances the separation of photogenerated charge carriers but also effectively increases the number of active sites; at the same time, Fe³⁺ acts as an electron trap to inhibit recombination, and the dominant active species (·O₂⁻ and h⁺) synergistically achieve efficient degradation. This work provides new insights for designing cost-effective transition metal-doped bismuth-based photocatalysts.</p>