<p>The nano zerovalent iron (NZVI) is synthesized in bare and polyethylene glycol (PEG)-stabilized forms. The results of XRD, UV–Vis spectroscopy, and FTIR analyses support the synthesis and stabilization of the nanomaterial by PEG in desired forms. The scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis revealed the formation of spherical nanoparticles (∼ 50 nm) and nanoplates (~ 20nm) morphology with ≥ 66% ZVI. To evaluate the performance of PEG-NZVI for wastewater treatment, adsorption, and reduction of Cr(VI), these processes are monitored using UV–Vis spectroscopy and cyclic voltammetry (CV). On the removal of Cr (VI), the impact of various parameters like adsorbent dose, initial Cr (VI) concentration, pH, interferents, and stabilizing agents is assessed. The reusability and stability of PEG-NZVI towards Cr (VI) removal are also established. The exceptional 100% removal of 10 ppm Cr (VI) from real water samples is achieved within 3 min, following second-order kinetics, under the conditions of PEG (6k)-NZVI = 0.16 g L⁻¹, room temperature, and pH = 2.0. Even for higher amounts (25–100 ppm), the complete removal time is just 5 min. The Cr (VI) removal activity of the prepared iron-based adsorbents followed the order: PEG-NZVI (100%) &gt; bare NZVI (92.5%) &gt; powder ZVI (17.9%). The use of PEG-NZVI for the treatment of tannery wastewater clearly demonstrates the effectiveness of the proposed methodology.</p> Graphical Abstract <p></p>