One of the major challenges in developing direct hydrazine fuel cells (DHzFCs) is the creation of highly efficient, robust, and inexpensive electrocatalysts with a superaerophobic property for the hydrazine oxidation reaction (HzOR). Herein, a cobalt phosphide nanowire array (CoP-NWA@CP) is grown on a carbon paper substrate as a highly efficient electrocatalyst for the HzOR in alkaline medium, which features a superaerophobic surface that is highly antigaseous and conducive to nitrogen evolution (a gaseous byproduct of the HzOR). The catalyst demonstrates a significant HzOR performance with an onset potential of −61 mV (vs RHE), an ultralow overpotential of −32 mV@10 mA cm −2 , and superior stability with little current density loss over 10,000 s at an overpotential of 0.42 V (vs RHE). The remarkable HzOR performance of the CoP-NWA@CP catalyst is attributed not only to its high intrinsic activity but also to its nanowire array design, which offers a large specific surface area and rapid electron and mass transfer, as well as its superaerophobic surface wettability to expedite the release of N 2 from the catalyst surface. Furthermore, a DHzFC is constructed using the CoP-NWA@CP catalyst as the anode and commercial MnO 2 as the cathode, which delivers a high open-circuit voltage of 0.905 V, a remarkable power density of 300 mW cm −2 , and 95% retention after 12.5 h operation, suggesting great potential of CoP-NWA@CP in practical applications.