<p>Heavy metal contamination of soil and water resources poses a significant global environmental challenge. <i>Brassica juncea</i> L. is a promising candidate for phytoremediation due to its high biomass and metal tolerance. However, a quantitative understanding of its metal-specific uptake kinetics and translocation patterns under realistic conditions is essential for optimizing remediation strategies.</p><p>This study investigated the uptake, translocation, and kinetic modeling of lead, nickel, zinc, and mercury in <i>Brassica juncea</i> L. cv. Balady cultivated in soil irrigated with industrial wastewater over 90&#xa0;days. The plant exhibited distinct metal-specific remediation strategy. Zinc and Ni showed the highest accumulation, with significant translocation to shoots, indicating strong phytoextraction potential. In contrast, Pb and Hg were primarily sequestered in the roots, suggesting a predominant role in phytostabilization. A first-order kinetic model effectively described the temporal uptake, demonstrating an excellent fit for Ni (R² = 0.9983) and a strong fit for Hg (R² = 0.8755). The phytoremediation potential was quantitatively confirmed by the bioconcentration factor (BCF) and translocation factor (TF), with Zn showing the highest root concentration (BCF = 5.92) and Hg uniquely exhibiting a TF &gt; 1. <i>Brassica juncea</i> proves to be a versatile species for managing multi-metal contamination, capable of both phytoextraction and phytostabilization depending on the target metal. The validated kinetic models provide a predictive framework for estimating metal accumulation, thereby enhancing the planning and efficiency of <i>B. juncea</i>-based phytoremediation interventions in wastewater-impacted environments. This work bridges the gap between controlled experimentation and field application by integrating empirical data with mathematical modeling.</p>