Electrocatalytic nitrate reduction to ammonia (NO₃RR) is a promising approach to recycle nitrogen from nitrate pollutants, yet it remains challenged by low Faradaic efficiency and insufficient NH₃ production. Herein, Cu-doped nanoporous Co₂P (np-Co_2−xCu_xP) is reported as electrocatalyst for NO₃RR, achieving an ammonia yield rate of 30.6 mg h⁻¹ cm⁻² with a Faradaic efficiency of 93.4% at −0.3 V vs. RHE. In-situ spectroscopic analyses indicate that Cu incorporation modifies the surface electronic structure, resulting in the promotion of *H adsorption and *NO₂⁻ hydrogenation, thereby facilitating efficient ammonia generation.