Research on extremely efficient bifunctional electrocatalysts to promote both the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics is of paramount importance for the advanced rechargeable Zinc-air battery. Herein, a cost-effective and scalable strategy is proposed for the synthesis of FeCo alloy nanoparticles embedded in the nitrogen-doped carbon nanotubes-grafted nitrogen and sulfur co-doped carbon nanofibers (FeCo-NSCNF@NCNT). The newly obtained catalyst with three-dimensional (3D) interconnected network architecture demonstrates high ORR and OER catalytic activities as evidenced by the high half-wave potential for the ORR and a low overpotential for the OER, which can be comparable to the commercially available well-known precious metal catalysts. With the catalyst employed as the air electrode of an assembled Zinc-air battery, narrow charge-discharge voltage gap and superb cycling stability (over 100 h) at the current density of 10 mA cm−2 can be obtained, signifying the promising application in the next generation of rechargeable metal-air batteries.