Membrane bioreactors (MBRs), which offer great promise for resource recovery and bioenergy production, have become a game-changing technology in wastewater treatment. MBRs are perfect for both municipal and industrial wastewater applications because they combine membrane filtration with biological treatment to provide high-quality effluent and improved biomass retention. This dual capability makes it possible to remove organic pollutants effectively while also capturing valuable by-products like biogas, nutrients (phosphorus and nitrogen), and reusable water. Recent developments in reactor designs, membrane materials, and operating techniques have greatly increased the MBR systems’ economic viability and energy efficiency. Particularly, anaerobic membrane bioreactors (AnMBRs) are drawing interest due to their capacity to generate methane-rich biogas in low-energy settings, which helps treatment plants become energy self-sufficient. Furthermore, the recovery of resources from sludge and effluent streams has been further improved by the integration of membrane-based techniques such as pressure-retarded osmosis and forward osmosis. Notwithstanding these benefits, obstacles, including membrane fouling, expensive startup costs, and intricate system administration, still prevent broad adoption. Fouling mitigation techniques, the creation of affordable membranes, and hybrid systems that integrate MBRs with other cutting-edge technologies are the main areas of ongoing study. The potential of MBRs to support the objectives of the circular economy by converting waste streams into sources of electricity, clean water, and valuable nutrients is what will determine their future.