The urgent need for sustainable and renewable energy sources has intensified research on biodiesel as an alternative to fossil fuels. Among various production pathways, the transesterification reaction is a widely adopted method for converting feedstock oils into fatty acid methyl esters (FAMEs). Traditional homogeneous catalysts, while effective, face critical challenges such as complex separation, limited reusability, and significant energy requirements. Nanocatalysts have emerged as a transformative solution, offering high surface area, enhanced catalytic activity, and improved reaction kinetics that significantly boost biodiesel yields. Metal oxide nanocatalysts, including calcium oxide (CaO), zinc oxide (ZnO), and cerium oxide (CeO), as well as carbon-based and zeolite nanocatalysts, have demonstrated superior performance due to their tunable properties and stability. In addition, magnetic nanocatalysts and biochar-based materials provide efficient recovery options and align with green chemistry principles. Nanocatalysts optimize critical process parameters such as catalyst loading, methanol-to-oil ratio, and reaction temperature, resulting in biodiesel yields exceeding 90% under mild conditions. Studies have highlighted their ability to lower activation energy, enhance selectivity, and reduce overall process costs by allowing multiple reuse cycles without performance degradation. However, challenges such as high fabrication costs, particle uniformity, and potential environmental impacts must be addressed for widespread adoption. Future research directions include the development of cost-effective green synthesis methods, hybrid catalytic systems integrating enzymatic and nano components, and the use of non-edible feedstocks to enhance sustainability. By combining high catalytic efficiency, reusability, and environmental benefits, nanocatalysts represent a breakthrough in biodiesel production technology. Their potential to simplify purification, reduce waste, and enable scalable, eco-friendly processes positions them as a key driver in the global shift toward renewable energy solutions.