In this work, a novel single-atom alloy electrocatalyst (SAAE) was developed for enhanced electrocatalysis in next-generation energy technologies. The catalyst, composed of single-atom Rh and bulk Ni on FeV3O8 support, overcomes challenges related to stability and efficiency in electrochemical reactions. The work function difference between Rh and Ni, as confirmed by computational and synchrotron-based analysis, facilitates superior electric polarization and ohmic contact with FeV3O8. The FeV3O8@RhNi demonstrates outstanding performance in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs), with high half-wave potential (0.90 V) and low overpotential (120 mV at 10 mA cm−2). In zinc-air batteries, it maintains a stable discharge–charge voltage gap, specific capacity of 810 mAh·g−1, peak power density of 186 mW·cm−2 at 320 mA·cm−2, and cycle stabilities exceeding 859 h at 10 mA·cm−2. The catalyst also proves its durability in flexible zinc–air batteries, indicating its potential for efficient electrocatalytic reactions in emerging energy technologies.