Electrochemical N2 reduction to NH3 has been considered as a promising sustainable and clean process to replace the conventional Haber–Bosch process. However, the development of efficient and stable electrocatalysts with superior activity for the electrochemical N2 reduction reaction (NRR) remains a great challenge. In this work, a composite of MoS2 nanodots highly dispersed on reduced graphene oxide (MoS2 NDs/RGO) is prepared as an effective catalyst for electrochemical N2 fixation. Benefiting from the homogeneous dispersion of the MoS2 NDs on RGO and the strong C–S–C bridging bonds between them, this composite can provide abundant active sites and boost the electron transfer in the reaction. As a result, the MoS2 NDs/RGO hybrid achieves a remarkable faradaic efficiency of 27.93% and NH3 yield rate of 16.41 μg h–1 mgcat.–1 at ambient conditions, which is much better than the NRR performance achieved by MoS2 nanosheets on reduced graphene oxide (MoS2 NS/RGO). Additionally, the catalyst shows high electrochemical selectivity and stability.