Despite global efforts to mitigate climate change and transition towards renewable energy sources, fossil fuels continue to meet 80% of the world’s energy demands. Because fossil fuel supplies are finite and they have a significant impact on CO2 emissions and global warming, immediate action is required. Utilizing biomass energy, particularly from organic waste and wastewater, presents a chance to reduce climate damage and address the energy crisis. The biotechnological approach of microbial electrolysis has shown great promise in addressing two critical environmental problems such as wastewater treatment and energy production. Over the past 20 years, research has focused on microbial electrolysis cells (MECs), which present a viable approach to generate methane and hydrogen gas from wastewater. The exponential increase in papers pertaining to MEC highlights the growing interest in and promise of this technology. This chapter offers a thorough examination of microbial electrolysis, including its foundational ideas, working processes, uses, and potential future developments. Before exploring the special benefits of microbial electrolysis, an outline of microbial electrochemical systems, such as microbial fuel cells and MECs, is given. To improve sustainability and energy efficiency, the integration of microbial electrolysis with renewable energy sources like solar and wind power is being investigated. Novel electrode materials, microbial consortia, and reactor topologies are among the recent technological advances that are studied for their potential to enhance performance and scalability. The chapter ends by highlighting the major issues and prospects for additional study and advancement in this quickly developing field, with a focus on the potential applications of microbial electrolysis in decentralized energy production and environmentally friendly wastewater treatment.