The inert basal plane of molybdenum disulfide (MoS₂) restrains its further hydrogen evolution reaction (HER) performance. This work attempts ion irradiation to activate inert basal plane of MoS₂ nanosheet to improve its electrocatalytic performance. Experimental results demonstrate the sulphur vacancies generated by ion irradiation on the basal plane of MoS₂ mainly boost the efficiency of HER performance. The moderate fluence of carbon ion irradiation gains the optimum HER performance with an onset potential of 77 mV and Tafel slope of 66 mV/dec.