Carbon-based materials are cost-effective and eco-friendly but have limited sensitivity for detecting heavy metals. Density Functional Theory (DFT) is employed to design materials suitable for sensing, based on their interaction with analytes. Oxidized carbon black embedded with silver nanoparticles (OCB-Ag) is designed and studied via DFT, showing promising conductivity and arsenic interaction. Experimental validation confirmed its efficacy. The OCB-Ag nanocomposite was synthesized via in-situ preparation and used as an electrode material for arsenic detection. Characterization via UV–Visible spectroscopy and X-ray diffraction confirmed successful synthesis. Electrochemical interaction with arsenite was studied using square wave anodic stripping voltammetry. The OCB-Ag platform exhibited a linear current response up to 600 ppm of As3+, with a low limit of detection (0.01 ppm) and good sensitivity (5.9 µA ppm−1). The detection limit of electrode material for As3+ lies within the threshold value set by world health organization for drinking water. The experimental results validated the concept of designing electrochemical sensing platform through DFT, and its potential for detection of As3+.