<p>In the present study, we investigated arsenic (As³⁺) sensing using the electrochemical approach of square wave voltammetry (SWV). We have prepared the sensing electrode by utilising gold nanoparticles on the glassy carbon surface for the sensitive and selective detection of As³⁺ ions, followed by optimisation of key SWV sensing parameters. The proposed sensor exhibits remarkably low detection limits (LOD) of 0.15 ppb, within the linear range of 10–50 ppb with R² = 0.98, significantly surpassing those reported in previous studies, enabling the accurate detection of even trace amounts of arsenic. The sensor demonstrates excellent selectivity for As³⁺ ions, minimising interference from other ions commonly found in water samples, and ensures reliable and accurate detection of arsenic, even in complex matrices. Further, the stability and repeatability make it suitable for long-term monitoring applications. The sensor’s performance aligns well with the World Health Organisation’s stringent drinking water limit of 0.13 µM/10 ppb, making it a promising tool for practical arsenic monitoring in various water sources. By combining advanced nanomaterials and electrochemical techniques, this innovative sensor offers a powerful solution for the early detection and mitigation of arsenic contamination, safeguarding public health and environmental quality. </p> Graphical Abstract <p></p>