The sustainable management of hazardous industrial residues has become a pressing challenge in environmental science. In this study, a novel red mud/polyvinyl chloride (PVC) composite was synthesized and systematically evaluated as an adsorbent for the removal of Malachite Green (MG), a carcinogenic cationic dye, in a fixed-bed column system. The composite was characterized by SEM, FTIR, and XRF analyses, confirming a heterogeneous matrix with abundant functional groups and active adsorption sites. Dynamic adsorption experiments were conducted under varying initial dye concentrations (50 and 100 mg/L), and the breakthrough curves were analyzed using Thomas, Yoon–Nelson, and Adams–Bohart models. The results demonstrated a maximum adsorption capacity of 81.87 mg/g at 100 mg/L, with high model correlation coefficients (R² ≈ 0.98) indicating strong predictive accuracy. Comparative evaluation with other adsorbents highlighted the superior performance and structural stability of the red mud/PVC composite under continuous flow conditions. Beyond effective dye removal, the integration of red mud into PVC not only reduces the environmental burden of bauxite residue disposal but also provides a scalable, low-cost adsorbent aligned with circular economy principles. This study offers new insights into polymer–industrial waste composites as promising candidates for sustainable wastewater treatment applications.