Electrochemical reactions facilitated by microorganisms enable bio-electrochemical systems (BESs) to produce biofuel, clean wastewater, and generate bioelectricity. The performance level of these systems heavily depends on the electron transport processes between microorganisms and electrodes. Three electron transfer mechanisms operate simultaneously in BESs: direct electron transfer (DET), mediated electron transfer (MET), and nanowire-based conduction. The transfer of electrons from Shewanella and Geobacter to electrodes occurs through direct electron transfer utilising conductive pili and cytochromes that reside in their outer membrane layers. Better power generation within MFCs heavily depends on this technique. The electron transfer method of MET functions through soluble redox mediators, such as flavins and quinones, which enable electron movement between microbial cells and electrode surfaces. Several bacteria transfer electrons through nanowires that conduct electrons from microbial networks to the electrode surface. The advancement of BES technology requires an optimised understanding of electronic channels for higher efficiency levels in commercial applications. Researchers will advance future work by creating new electrode materials in combination with enhanced extracellular electron transfer (EET) microbial strains to achieve improved conductivity and biocompatibility. These developments will yield innovations in renewable energy systems, environmental remediation procedures, and sustainable bioproduction methods.