Selective and efficient ammonia (NH₃) production using an electrocatalytic nitrate reduction reaction (ECNtRR) under ambient conditions provides a green and promising alternative to the traditional energy-intensive Haber–Bosch process. The challenge is in design and controlled syntheses of efficient electrocatalysts with high selectivities, high NH₃ yield rates (Y_NH3) and long-term stabilities. Here, a freestanding three-dimensional graphdiyne-hollowed FeCoNi Prussian blue analog electrode (h-FeCoNi PBA@GDY) with highly selective and active interfaces was synthesized by in situ growth of a GDY layer on the surface of h-FeCoNi PBA and used for the ECNtRR in alkaline solution at ambient temperatures and pressures. The experimental results demonstrated that the uniquely incomplete charge transfer between metal atoms and GDY effectively enhanced the intrinsic activity and increased the number of active sites of the electrocatalyst and promoted fast redox switching and high-density charge transport at the interface, which resulted in high selectivity, activity and stability for the ECNtRR. The results indicated that the electrocatalyst showed a Faraday efficiency (FE) of 95.1% with a Y_NH3 of 1015.5 μmol h⁻¹ cm⁻² and excellent stability.