Supercapacitors are garnering considerable interest owing to their high-power density, rapid charge-discharge capability, and long cycle life. Among the various materials explored, biomass-derived carbon nanomaterials stands out as a sustainable and cost-effective choice, thanks to its natural abundance and eco-friendly characteristics. This review delineates recent advances in the synthesis of zero-dimensional (0D) carbon nanomateirlas from various biomass precursors via hydrothermal assisted synthesis. It offers a comprehensive discussion on the factors affecting the synthesis of 0D carbon nanomaterials, including precursor type, concentration, reaction temperature, and time. Furthermore, the review underscores the impact of different activation methods on the morphology and electrochemical performance of 0D carbon nanomaterials. Finally, we outline the challenges and future prospects of utilizing biomass-derived carbon nanomaterials in supercapacitor applications, emphasizing the importance of optimizing synthesis parameters to attain the desired material properties.