The increasing dependence on fossil fuels has accelerated greenhouse gas emissions, highlighting the urgency for sustainable energy alternatives. Biofuels offer a renewable, eco-friendly solution, and recent advances in nanotechnology have significantly improved their production efficiency. This review examines how nanomaterials—such as graphene, carbon nanotubes, metal nanoparticles, nanocomposites, and nanoscale biochar—enhance the conversion of feedstocks into biodiesel, biogas, biohydrogen, and bioethanol. These nanomaterials improve catalytic activity, conversion efficiency, product yield, and purity. Specifically, nanocatalysts enhance biodiesel transesterification, optimize anaerobic digestion for biogas, and promote microbial synthesis pathways for biohydrogen and bioethanol. The review also addresses synthesis methods, material functionalization, global adoption trends, environmental implications, and risk management strategies. Despite the promise, challenges like nanotoxicity, lifecycle assessment, and scalability remain. Future research should prioritize cost-effective, biodegradable, and scalable nanomaterials, comprehensive regulations, and increased investment in green nanotechnology to ensure safe and sustainable biofuel production.