<p>Polystyrene (PS) is widely used in small plastic products, contributing significantly to the amount of plastic waste generated worldwide. Thus, the development of simple and practical strategies to prepare high-value-added products from waste PS is of great importance. In this study, fibrous cation-exchange materials (PS-SO₃H) were prepared by sulfonating waste PS and evaluated in terms of their heavy-metal-ion adsorption properties. The PS-SO₃H fibers demonstrated excellent Pb²⁺ adsorption, with a maximum adsorption capacity (<i>q</i>_max) of 240&#xa0;mg/g at pH 4–5. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the successful introduction of sulfonic acid groups into the PS fibers and formation of a porous surface, which enhanced the availability of adsorption sites. Mixed-ion adsorption experiments (Cd²⁺, Cu²⁺, Zn²⁺) revealed the greatest affinity for Pb²⁺ owing to its large ionic radius and high charge density. Adsorption followed a second-order kinetic model, and the Langmuir isotherm yielded a <i>q</i>_max of 256.41&#xa0;mg/g. Fixed-bed column experiments indicated that the height-to-diameter ratio significantly influenced adsorption. The Bohart–Adams and BDST models effectively predicted column performance. Desorption tests showed 1.0-N HNO₃ achieved over 90% desorption efficiency. The results demonstrate the potential of PS-SO₃H fibers as efficient adsorbents for Pb²⁺ removal, indicating applications in wastewater treatment and environmental remediation.</p>