Developing large-scale and highly efficient oxygen reduction reaction (ORR) catalysts acts a vital role in realizing wide application of metal-air batteries. Here, we propose a gas-foaming strategy to fabricate sustainable and 3D hierarchically porous N-doped carbon with high specific surface area and abundant defects sites derived from biomass. The obtained catalyst exhibits prominent ORR property with higher half-wave potential (0.861 V) and slightly lower kinetic current density (32.44 mA cm−2), compared to Pt/C (0.856 V and 43.61 mA cm−1). Furthermore, employing it as catalyst of air cathode, the Al-air battery delivers remarkable discharge performance with excellent power density of 401 mW cm−2, distinguished energy density of 2453.4 Wh kg−1 and extremely high open-circuit voltage of 1.85 V among the reported metal-air batteries in the literatures. This gas-foaming strategy for full utilization of biomass affords a chance to explore scalable advanced catalysts in metal-air battery.