This chapter presents a comprehensive review of recent advancements in polymeric mixed matrix membranes (MMMs) for mitigating fouling in water reclamation. MMMs, composed of a polymeric matrix embedded with organic or inorganic nanofillers, offer a promising approach to overcoming the limitations of conventional membranes. The chapter discusses the fundamentals of MMMs, including transport mechanisms and classifications based on filler type (inorganic, organic, hybrid, and bio-fillers), while addressing challenges such as particle agglomeration and ensuring long-term stability. Various fabrication techniques, including phase inversion and electrospinning, are examined alongside key performance evaluation parameters like pure water permeability, contaminant rejection, and fouling ratios. Advanced characterisation methods, such as SEM, TEM, AFM, FTIR, and Zeta potential analysis, are highlighted. A detailed analysis of fouling mechanisms (organic, inorganic, biofouling, and colloidal) is provided, followed by an exploration of innovative material designs for fouling mitigation, including graphene oxide, carbon nanotubes, and metal–organic frameworks. The chapter concludes by addressing current challenges and outlining future research directions for optimising MMMs in sustainable water reclamation technologies.