The increasing global energy demand, combined with the urgent environmental concerns associated with conventional energy sources, presents significant obstacles to the sustainable advancement of modern society. Addressing these challenges has driven research efforts toward developing affordable and biodegradable alternatives that can replace toxic and expensive materials in energy technologies. Bionanocomposites have emerged as a promising solution in this arena, garnering substantial interest due to their unique electrochemical characteristics, renewable origins, and environmental compatibility. This book chapter delves into the advancements in bio-nanocomposites and their potential to revolutionize energy storage and conversion devices, such as batteries, supercapacitors, solar cells, and fuel cells. The focus is on the integration of biopolymers with nanostructured inorganic materials to enhance energy storage and conversion efficiency. Specifically, improvements have been observed in the development of key components like electrodes, separators, current collectors, and electrolytes. These improvements are primarily attributed to the ability of biopolymer-based matrices to facilitate better loading of active materials and the creation of uniform, porous structures that optimize electrochemical performance.