Bacteria can naturally synthesize a wide range of biopolymers that have appealing material properties for numerous applications. In the past decade, the development of green electronics based on bacterial polymers has gained major attention. Polymer electrolytes are key components in electrochemical devices owing to their mechanical properties, thermal stability, and ionic conductivity. The present review focuses on the recent progress of bacterial-polymer-based electrolytes and their applications in electrochemical energy conversion and storage. First, we described the ion transfer mechanism of polymer electrolytes and the multiple approaches for improving ionic conductivity and mechanical properties. Then, we summarized the composition, performance, and approaches applied for the development of multiple bacterial polymer electrolytes, namely, polysaccharides, polyanhydrides, and polyesters. Lastly, the practical applications of bacterial-polymer-based electrolytes in electrochemical energy storage and conversion, namely, fuel cells, batteries, supercapacitors, and other electrochemicals, are reviewed. Bacterial polymer electrolytes are presented as a fruitful, eco-friendly, and high-performance alternative for traditional solid polymer electrolytes.