AbstractElectroless deposition technique was employed to coat the surface of a glassy carbon electrode (GCE) with nanoparticles of gold (AuNPs). Afterward, sulfur (S) components were immobilized onto this AuNPs/GC electrode via an in‐situ chemisorption approach that considerably enhanced the catalytic activity, conductivity, and persistent durability of the electrode. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS) were used to characterize the modified electrode surface. The experimental results indicated that the S−AuNPs/GC electrode exhibits outstanding catalytic activity for the selective detection of H₂O₂ (HP). SWV measurements showed that the electrochemical sensor has a wide linear range of 10 to 2500 μM and a heightened sensitivity of 50.08 μA mM⁻¹ cm⁻². The proposed HP sensor demonstrated adequate repeatability and durability, as well as interference‐free quantitative analysis capability.