 Development of stable, high-performance and cost-effective bifunctional electrocatalysts that can replace baseline Pt- and Ir-based catalysts has been a central theme in metal–air batteries. Along this direction, transition metal-based oxides and nitrides have attracted attention due to their abundance, stability, and low cost. Here, Mn nitride, fabricated via annealing of Mn powder in N2, is investigated for the first time as a candidate bifunctional electrode for rechargeable Zn–air batteries (ZABs). Three samples were prepared by nitridation of a Mn precursor, with particle size <100 μm, at 1100 °C for 4–30 h. The morphology and microstructure of the fabricated samples were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), and X-ray diffraction (XRD). Phase quantification for all samples was performed using Rietveld-based fitting. The samples treated for 4 and 10 h had the largest fraction (~75%) of nitride phases (Mn4N and Mn6N2.58); the remaining material was primarily MnO. The nitride phases were not pure, but contained oxygen, resulting in the formation of pseudobinary phases. The oxygen reduction/evolution reaction (ORR/OER) performance of all samples was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte (0.1 M KOH). Among all the catalysts, the sample treated for 10 h exhibited the most positive ORR onset potential (−0.038 V vs. Hg/HgO) with good stability. The catalyst was incorporated into a practical ZAB and displayed a battery efficiency of 52.7% after 14 h of charge–discharge cycling (1 h/cycle) at a current density of 7.5 mA cm−2.