Material novelty is momentous for electrocatalyst in striding into a renewable energy era. Oxygen evolution reaction (OER) is of great significance for hydrogen production via water electrolysis, but has a high energy barrier that limits the energy conversion efficiency. Herein we report a highly-efficient and long-term durable NiFePB OER electrocatalyst, which composes of unique porous amorphous conductive solids with finely tuned nonmetal elements. The NiFePB phase formation is confirmed with X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) characterizations determine a porous amorphous structure. The outstanding metallic conductivity and corrosion resistance properties are simulated with density functional theory (DFT) calculations. Benefiting from these unique features, the NiFePB exhibits an extraordinarily low overpotential of 197 mV to reach an OER current density of 10 mA/cm2 and 233 mV to reach 100 mA/cm2 under chronopotentiometry condition, with the Tafel slope harmoniously conforming to 34 mV/dec. The catalyst also has an impressive long-term stability, evidenced by a limited activity decay for more than 50-h in a wide current density range from 10 to 200 mA/cm2. This work strategically directs a way for heading up a promising energy conversion alternative.