<p>The selective capture of heavy metal ions is a persistent challenge in environmental remediation owing to the chemical similarities among metal ions and the need for high affinity, selectivity, and capacity. Biological systems have evolved efficient mechanisms to regulate metal ions, utilizing proteins such as phytochelatin, metallothionein, and lanmodulin. These biomacromolecules achieve affinity, selectivity, and capacity for metal ions at biologically relevant levels through well-organized structural motifs, inspiring the design of synthetic polymers with biomimetic functions. This focus review provides an overview of research on heavy metal-binding proteins and explores how these proteins inspired researchers to develop bioinspired and biointegrated materials. First, key structural and thermodynamic features of heavy metal-binding proteins and their roles in metal detoxification and homeostasis are discussed. Then, recent advancements in emerging materials that mimic these biological functions using synthetic peptides, polymers, and peptoids are highlighted. Finally, we review integrated systems that directly incorporate biological components with synthetic polymers to create advanced heavy metal adsorbents. Together, these approaches illustrate how bioinspired and biosynthetic integration strategies are driving innovations in heavy metal ion capture technologies. Continued interdisciplinary research promises to deliver next-generation materials with improved efficiency, specificity, and environmental compatibility for real-world applications.</p>