Bioelectrochemical conversion is an emerging interdisciplinary field that integrates microbiology, electrochemistry, and environmental engineering to harness the metabolic capabilities of microorganisms for energy and resource recovery. At the heart of this technology lie bioelectrochemical systems (BES), such as microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), which utilize electroactive microbes to catalyze oxidation–reduction reactions at electrode surfaces. These systems offer a promising approach for converting organic waste, wastewater, and carbon dioxide into valuable products, such as electricity, hydrogen, methane, and biofuels, under mild operating conditions. The versatility and sustainability of bioelectrochemical conversion make it a compelling alternative to conventional energy and waste treatment technologies. This introductory overview highlights the fundamental principles, key components, and potential applications of bioelectrochemical systems, laying the groundwork for their broader adoption in clean energy generation, waste valorization, and environmental remediation.