Effectively improving the selectivity while reducing the overpotential over the electroreduction of CO₂ (CO₂ER) has been challenging. Herein, electronegative N atoms and coordinatively unsaturated Ni-N₃ moieties co-anchored carbon nanofiber (Ni-N₃-NCNFs) catalyst via an integrated electrospinning and carbonization strategy are reported. The catalyst exhibits a maximum CO Faradaic efficiency (F.E.) of 96.6%, an onset potential of −0.3 V, and a low Tafel slope of 71 mV dec⁻¹ along with high stability over 100 h. Aberration corrected scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy identify the atomically dispersed Ni-N₃ sites with Ni atom bonded by three pyridinic N atoms. The existence of abundant electronegative N dopants adjoin the Ni-N₃ centers in Ni-N₃-NCNFs. Theoretical calculations reveal that both, the undercoordinated Ni-N₃ centers and their first neighboring C atoms modified by extra N dopants, display the positive effect on boosting CO₂ adsorption and water dissociation processes, thus accelerating the CO₂ER kinetics process. Furthermore, a designed Zn-CO₂ battery with the cathode of Ni-N₃-NCNFs delivers a maximum power density of 1.05 mW cm⁻² and CO F.E. of 96% during the discharge process, thus providing a promising approach to electric energy output and chemical conversion.