Electrochemiluminescence (ECL) of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions (As(III)). Cyclic voltammetry (CV) was applied as the proposed technique to study luminol’s electrochemical behavior and to evaluate the arsenic’s effect in the ECL system, while hydrogen peroxide (H2O2) served as a co-reactant to enhance luminol’s light emission under alkaline conditions. To achieve optimal electrode performance, key parameters including pH, scan rate, and the concentrations of H2O2 and luminol were carefully optimized. The presence of As(III) induced a quenching effect on the luminol/H2O2 ECL system, leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol·L–1 to 150 µmol·L–1. The system demonstrated a low detection limit of 1.21 nmol·L–1 and exhibited excellent repeatability with a relative standard deviation of 2.27%, highlighting its sensitivity and reliability for As(III) detection. A key advantage of this study was the successful use of commercial bare electrodes, which were readily available and required no modifications, proving their effectiveness for ECL-based arsenic sensing. The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity, as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state, whereas other potential metal ion interferences were more likely to form solid metal (hydro)oxides. Furthermore, the developed sensor was successfully applied for As(III) detection in a seawater matrix, demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications. © 2026 Xiamen University and Chinese Chemical Society. This is an open access article under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/).