A Zn-air battery is a potential next-generation energy storage device owing to its extremely high theoretical energy density. Currently, it is important to explore non-precious metal electrocatalysts with high electroactivity and stability in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the development of Zn-air batteries. In this work, porous (Ni,Co)Se2 nanosheets were synthesized by selenizing NiCo2O4 nanosheets. By regulating the conductivity and morphology of the sample, the prepared porous (Ni,Co)Se2 nanosheets show enhanced electrocatalytic activity for OER and ORR compared to NiCo2O4 nanosheets. The aqueous Zn-air battery using porous (Ni,Co)Se2 nanosheets as the air cathode exhibits superior charge and discharge performance (1.98 V for charging and 1.17 V for discharging), high specific capacity (770 mAh/g), and excellent cycle stability (140 h). These results indicate that the porous (Ni,Co)Se2 nanosheets are suitable as a bifunctional electrocatalyst for future Zn-air batteries.