Highly efficient noble-metal-free electrocatalysts are urgently explored for high energy density and safe metal-air batteries. Herein, an ingenious Co-CoO@NAC is prepared for this purpose by anchoring Co single atom on both CoO nanoparticle and nitrogen-doped active carbon (NAC), where synergistic interaction among Co atoms, CoO particles and NAC plays a significant role for excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Moreover, the primary zinc-air battery (ZAB) with the Co-CoO@NAC as a cathode catalyst shows a high open circuit voltage (OCV) of 1.449 V, a specific energy density of 721 mA h/g and a maximum power density of 164 mW/cm. The rechargeable ZAB with this catalyst displays a low voltage gap of 0.773 V at 10 mA/cm and stable cycling performance. This work provides a novel tactic to design elaborate high-efficient and promising bifunctional catalysts with non-noble metal atom and metal oxide for metal-air batteries.