Abstract: The growing demand for environmentally sustainable ground improvement techniques has led to increased interest in bio-mediated soil treatment methods. These approaches utilize microbial activity to enhance soil properties, offering a low-carbon alternative to conventional chemical grouting and cement stabilization. This study examines the effectiveness of microbial-induced bio-clogging in reducing soil permeability and hydraulic conductivity, with a focus on the role of microbial in producing dextran-based biofilms. Experimental investigations, including constant-head permeability tests and microstructural analyses using scanning electron microscopy (SEM), reveal that microbial activity significantly reduces soil permeability by clogging pore spaces with extracellular polymeric substances. The findings also highlight that factors such as microbial concentration, nutrient availability, and application methods (e.g., injection, mixing, and pouring) influence the spatial distribution and efficiency of bio-clogging. Notably, dextran production increases after an initial settling period of approximately 5–7 days, contributing to an exponential reduction in hydraulic conductivity. These results demonstrate the potential of microbial soil improvement as a sustainable, adaptive solution for seepage control and infrastructure resilience, particularly in environmentally sensitive and permeable soil conditions.