Herein, a Fe³⁺-loaded aminated polypropylene fiber has been reported as an efficient phosphate adsorbent. The remarkable phosphate removal ability of the fiber is due to Fe³⁺ immobilization, and it demonstrates a maximum adsorption capacity of 33.94 mg·P·g^–1. Adsorption experiments showed that the fiber is applicable over a wide pH range from 2 to 9. Furthermore, the adsorption kinetics and isotherm data were consistent with the pseudo-second-order and Langmuir adsorption models, respectively. The adsorption equilibrium of the fiber for phosphate was reached within 60 min, indicating an efficient monolayer chemisorption process. Moreover, the adsorbent maintained prominent phosphate removal in the presence of competitive ions such as NO₃^– and Cl^–, exhibiting high selectivity. More importantly, the fiber demonstrated excellent reusability (5 times) and low adsorption limit below 0.02 mg·P·g^–1. In addition, the phosphate removal efficiency of the fiber can exceed 99% under continuous flow conditions. The adsorption mechanism was studied by X-ray photoelectron spectroscopy, showing that the adsorption of phosphate on the fiber mainly depended on the chemical adsorption of the modified Fe³⁺. Overall, this study proves that the fiber possesses many advantages for phosphate removal, including high adsorption efficiency, lower treatment limit, good recyclability, and environmental friendliness.