The flexible zinc-air batteries characterized by heightened flexibility, durability, and high electrochemical performance have been recognized as the most promising candidates for the next-generation wearable electronic products. Herein, a novel Fe3C/MnO heterostructure coupled with nitrogen-doped carbon (Fe3C/MnO-NC) derived from metal-organic frameworks (MOFs) is innovatively designed as a highly active bifunctional electrocatalyst. The Fe3C/MnO heterostructure in Fe3C/MnO-NC can effectively regulate the electronic structure to optimize the free energy of the related intermediates in the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), consequently improving the catalytic properties of liquid Zn-air battery with impressive power density and outstanding stability. The theoretical calculations reveal that the design of the heterogeneous Fe3C/MnO interface effectively tunes the electron distribution to optimize the adsorption energy of ORR/OER related intermediates and significantly promotes intrinsic ORR/OER activities. Notably, the flexible Zn-air battery was also assembled with the bifunctional Fe3C/MnO-NC electrocatalyst and the prepared polyacrylamide polyacrylic acid-glycerin composite gel polymer electrolyte (PAM-PAA-Gly GPE). The electrochemical results reveal that the constructed flexible Zn-air battery can achieve a remarkable open-circuit voltage of 1.50 V and sustain stable cycling for 48 h (288 cycles). This work not only sheds light on the effective utilization of Fe3C/MnO-NC catalysts but also highlights the potential of hydrogels in achieving high-performance wearable Zn-air batteries.