Hydroelectric nanogenerators (HENGs) utilize the synergy between conductive nanomaterials and hydrodynamic flow to generate electricity, but their applications are limited by low output power density. Here, a high-performance HENG is developed by employing single-layer MXene (SMX) nanosheets on wool cloth. The SMX-based HENGs exhibit a maximum energy density of 0.683 mW cm−2, a current of 1.994 mA, and a voltage of 0.687 V, sufficient to power small wearable electronics. Moreover, the hydrophilicity of the HENGs is maintained due to the addition oxidized ketjen black nanoparticles to the SMX matrix. This is attributed to the functional groups (e.g., –COOH and –OH) on OKB, which are important for efficient ion transport and maintaining a high steady-state power density. Important insights into energy generation for the development of high-efficiency HENGs for practical applications have been gained from numerical simulation using COMSOL multiphysics.@en