<p>In this study, a series of iron-based Prussian Blue Analogues (PBAs) were synthesised using ¹³⁷Cs as the model radioactive contaminant. The influence of various nitrogen-ligand metal species on the cesium adsorption performance was systematically examined through controlled experiments. Subsequently, an innovative composite hydrogel was engineered via a single-step polymerisation methodology, integrating guar gum (GG), borax, glycerol, and optimised PBA adsorbents. This approach capitalised on synergistic interactions between borate crosslinking, hydrogen bonding networks, and cesium-selective coordination sites, yielding a mechanically robust hydrogel with exceptional structural integrity and decontamination capabilities, while maintaining rapid manufacturing potential. The hydrogel exhibited unprecedented efficiency in removing cesium contaminants from heterogeneous surfaces, achieving removal efficiencies of 99.64% (glass), 99.50% (stainless steel), 99.62% (rubber), 99.27% (lacquered board), and 88.37% (cement), thereby demonstrating consistent performance across diverse substrate chemistries and surface topographies. Comprehensive mechanistic analysis revealed the dual functionality of the hydrogel coating: physical entrapment through viscoelastic adhesion and chemoselective ion capture via PBA coordination. These findings provide critical insights into surface-bound radionuclide remediation strategies, positioning this technology as a transformative solution for practical radioactive decommissioning operations and environmental remediation initiatives.</p> Graphical abstract <p></p>