Heavy metal contamination poses a critical threat to global water resources, necessitating the development of cost-effective and environmentally sustainable remediation strategies. Bioadsorbents derived from natural biomass provide an eco-friendly alternative to conventional physicochemical methods. This study evaluates the efficiency, adsorption mechanisms, kinetic behavior, and practical applicability of selected natural bioadsorbents—including agricultural waste, lignocellulosic residues, and biochar—for the removal of Pb(II), Cd(II), Cr(VI), and Cu(II) ions from contaminated water. Results of adsorption experiments indicate that these materials exhibit high metal uptake capacities, especially when modified or carbonized. Adsorption isotherms fitted best with the Langmuir model, suggesting monolayer chemisorption as the dominant mechanism. The study emphasizes the potential of natural bioadsorbents as scalable, low-cost, and sustainable solutions for heavy metal remediation.