<p>Owing to their inherent abundance, superior biocompatibility, and good biodegradability (fast degradation rate, complete mineralization without toxic residues), nanostructured biopolymers have emerged as highly promising materials for sustainable electronics, attracting extensive research attention in recent decades. However, biopolymers directly extracted from biorefineries often exhibit limited technological maturity, as many are still under development and currently fall short of the performance standards achieved by conventional synthetic or petroleum-derived polymers in key properties such as mechanical strength, durability, electrical resistance, and ionic conductivity. To overcome these constraints, researchers have utilized multiple processing techniques to shape biopolymers and functionally modify them into forms possessing the required properties for integration into electronic systems. This review first concisely outlines the intrinsic physicochemical properties of common biopolymer types and subsequently evaluates critical structuring and functionalization technologies for their electronic applications. We then examine biopolymer-based structural fabrication technologies, with particular focus on tissue-like and solid membrane shaping strategies, as these configurations are extensively utilized in diverse electronic components. We emphasize carbonization techniques and the strategic incorporation of functional components into biopolymeric matrices to tailor their electronic properties, enabling transitions from insulating to conductive or semiconductive states. These advancements are essential for the successful integration of biopolymeric materials into cutting-edge applications within green electronics and related material science fields. A systematic review of applications is presented, focusing particularly on the implementation of biopolymers as various functional components in portable energy storage devices. Finally, we highlight the potential of nanostructured biopolymers to advance green electronics, particularly in supercapacitors and ionic batteries, and propose future research directions focusing on bioinspired design principles and environmentally benign assembly techniques. This review will accelerate research on biopolymer-based portable energy storage systems, advancing the development of next-generation sustainable and eco-friendly electronic technologies.</p>