Microbial electrochemical technologies connect living microorganisms with electrical systems to enable sustainable processes. These systems use the natural electron transfer abilities of microbes to support clean energy generation, transform waste and pollutants, and recover valuable resources. Microorganisms act as living catalysts whose biological traits and energy requirements determine system performance. Recent advances have expanded these technologies toward chemical production and new electronic applications, while improved engineering has increased their readiness for practical use. At the same time, these systems offer a powerful platform for studying fundamental microbial processes in real time. This review outlines the biological foundations of microbe–electrode interactions, highlights current applications relevant to circular resource use, and identifies scientific and engineering challenges that must be addressed to unlock broader societal and economic benefits. The goal is to emphasize the growing potential of microbe–electrical interfaces to support transformative solutions for environmental sustainability.