Arc discharge plasma nitriding (ADPN) of stainless steel was achieved using the thermionic electrons generated from column arc discharge to ionize the working gas to form a high-energy plasma. The column arc current is a key influential factor in the ADPN technique. AISI 420 martensite stainless steel (420 SS) was nitrided at a low temperature of ~ 440 °C to improve its mechanical properties and corrosion resistance using a highly efficient low-pressure ADPN technique. The arc plasma was generated by applying arc currents ranging from 100 to 130 A. The results of arc currents on the microstructure, mechanical characteristics, tribological properties, and corrosion performance of treated layers were investigated. The results revealed that the nitrided layers are primarily composed of expanded martensite (αN), Fe4N and Fe2-3 N, and a high arc current leads to the formation of a compound layer composed of Fe2-3 N and Fe4N. The surface microhardness and wear resistance of 420 SS were greatly improved following ADPN compared with conventional plasma nitriding. The samples treated at the higher arc current have a thicker nitrided layer and a tough surface with a higher fraction of Fe2-3 N, which shows the best wear and corrosion performance.