Microbial fuel cell (MFC) is an emerging technology which can convert organic matter into electricity through the metabolic activities of microbes, showing significant potential in wastewater treatment. Various MFC designs, including single-chamber, upflow, and stacked configurations, are examined for their efficiency and scalability across worldwide. Single-chamber MFCs offer simplicity and cost-effectiveness, whereas upflow MFCs enhance mass transfer and bioenergy production despite higher energy consumption for fluid recirculation. Stacked MFCs, whether horizontally or vertically aligned, provide increased power densities and effective COD removal, with vertical configurations demonstrating cost-effectiveness and scalability for continuous operations. This chapter summarize the electron transfer mechanisms within MFCs, emphasizing direct and mediated electron transfer processes facilitated by microbial biofilms and nanowires. Additionally, the integration of MFCs with constructed wetlands and their role in bio-electroremediation present promising avenues for sustainable wastewater treatment and energy production. Future directions include the incorporation of photosynthetic microbes to create solar-powered MFC systems, potentially enhancing bioenergy generation efficiency.