Abstract: Agricultural phosphorus loss and phosphogypsum accumulation pose dual environmental challenges for phosphorus cycle. Controlling agricultural phosphorus loss is a critical component of watershed water quality management, which requires the development of efficient and recyclable phosphorus adsorption materials. To improve the solid-liquid separation efficiency and phosphate selectivity of phosphorus adsorbents, this study investigated the performance of iron-modified phosphogypsum (Fe-PG) for phosphorus removal from water. The physicochemical properties of Fe-PG were systematically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, and dynamic adsorption experiments. The results showed that Fe-PG exhibited significantly improved phosphorus adsorption performance under acidic to neutral pH range, reaching a maximum adsorption capacity of 36.06 mg g^-1 at pH 4. This enhancement was attributed to surface modification and iron ion incorporation. The resulting Fe-PG also exhibited a strong magnetic property (3.04 emu g^-1), allowing efficient solid-liquid separation using magnetic field. Adsorption kinetics and isotherm analyses revealed that phosphorus adsorption process of Fe-PG conforms to the quasi-second-order kinetic model and the Langmuir isotherm adsorption model, indicating that its phosphorus adsorption is mainly monolayer chemical adsorption. The pH, temperature, phosphorus concentration and coexisting anions in the water body have an important influence on the adsorption performance, especially under the interference of Cl^-, which reduced the phosphate uptake. After five cycles of use, the phosphorus adsorption performance of Fe-PG still maintains a high efficiency, indicating that it has good reusability. This study successfully transformed the industrial by-product phosphogypsum into a magnetic adsorption material, achieving resource recovery from solid waste while providing a promising approach for intercepting dissolved phosphorus from agricultural runoff.