High entropy materials (HEMs) are promising candidates as efficient hydrogen evolution reaction (HER) electrocatalysts, however, the facile fabrication of nanostructured HEMs over conventional catalyst supports remains a huge challenge. Herein, we report the in situ synthesis of FeCoNiCuMnN high entropy alloy nitrides (HEANs) with unique integrated nanowire/nanosheet architecture on carbon cloth (FeCoNiCuMnN/CC-400) by hydrothermal reaction and subsequent calcination at 400 °C under Ar/NH₃ conditions. The FeCoNiCuMnN nanosheets and nanowires connected with each other and were uniformly grown on the CC. A series of characterization studies have confirmed the formation of the FeCoNiCuMnN phases with uniform element distributions. FeCoNiCuMnN/CC-400 can be directly used as the electrocatalyst for alkaline HERs, and as a result, the FeCoNiCuMnN/CC-400 obtained an overpotential of 184 mV to achieve 10 mA cm⁻² and a small Tafel slope of 113 mV dec⁻¹. The long-term durability studies indicated that the current density was maintained at 23 mA cm⁻² in an alkaline electrolyte under continuous HER operations for 50 h, suggesting excellent corrosion and oxidation resistance.