Ambient electrocatalytic N₂ reduction reaction (NRR) provides an eco-friendly way for artificial NH₃ production, while an efficient NRR process requires active and stable electrocatalysts. In this communication, we exploit the spinel ferrite NiFe₂O₄ as a promising NRR catalyst. The developed NiFe₂O₄ nanocubes/reduced graphene oxide (NiFe₂O₄/RGO) exhibited an appealing NRR performance with an NH₃ yield of 32.2 μg h⁻¹ mg⁻¹ and a faradaic efficiency (FE) of 9.8% at −0.5 V (RHE), as well as a high catalytic durability. Mechanistic investigations revealed that the surface Fe atoms serve as key NRR active sites for favorable N₂ adsorption and H⁺ suppression. These findings may facilitate the understanding and exploration of Earth-abundant spinel ferrite catalysts for electrochemical dinitrogen fixation.