Arsenic contamination in groundwater poses a significant threat to public health and agricultural sustainability in Southern Punjab, Pakistan, where naturally occurring arsenic exceeds WHO safety limits. Traditional remediation techniques are often costly, energy-intensive, and environmentally unfriendly. Iron oxide nanoparticles (Fe₂O₃ NPs) have demonstrated significant potential for adsorbing heavy metals, particularly arsenic, from water and soil. The green synthesis approach using plant extracts minimizes chemical toxicity and enhances environmental compatibility. This study aimed to synthesize iron oxide nanoparticles using Moringa oleifera leaf extract, removing arsenic (As³⁺/As⁵⁺) from arsenic-affected regions in Southern Punjab. Iron oxide nanoparticles were synthesized via aqueous extraction of Moringa oleifera leaves, acting as a reducing and stabilizing agent. The nanoparticles were characterized using UV–Vis spectroscopy, FTIR, XRD, and SEM. Batch adsorption experiments were conducted under varying pH, contact time, and nanoparticle dosages. Groundwater samples were analyzed using atomic absorption spectroscopy. The green-synthesized Fe₂O₃ NPs exhibited spherical morphology with an average size of 20–40 nm. The maximum arsenic removal efficiency (92.6%) was observed at pH 6.5 within 60 minutes. The nanoparticles retained over 85% efficiency after three reuse cycles, indicating good stability and reusability. The study demonstrates that Moringa oleifera-mediated iron oxide nanoparticles provide an eco-friendly, cost-effective, and efficient solution for arsenic remediation in groundwater.