<p>Soil erosion is a significant geo-environmental challenge, causing destabilization of riverbanks and compromising infrastructure. Effective mitigation requires advanced soil stabilization techniques to prevent land loss, protect ecosystems, and reduce fugitive dust emissions contributing to air pollution. In this study, biochar-assisted biocementation enhances sand stability against erosion by applying urease-producing bacterial cell solutions to the soil surface layer. To achieve this goal, the erosion resistance of biocemented soil samples was examined through experimental testing in a wind tunnel under high-speed wind conditions, while subjecting the similarly treated specimens to flowing water velocity surpassing the critical threshold in a flume setup. Compared to biocemented sand samples (S₀BCS) with an 85.5% reduction in rate of erosion, sand–biochar composite specimens (S₂BCS) demonstrate a superior erosion rate reduction of 98.5%. Similarly, the incorporation of biochar into the biocementation method significantly enhances resistance to hydraulic shear due to running water, as evidenced by approximately 25% greater soil retention in biochar-amended specimens. The study also highlights biochar’s effectiveness in reducing NH₄⁺–N concentrations through adsorption mechanisms to mitigate groundwater contamination and eutrophication. The experimental investigation concluded that biochar, as a nutrient, showed minimal impact on ureolytic bacteria’s growth and metabolic activity. This strategy, as a sustainable and environmentally friendly approach, has the potential to reform soil preservation practices and contribute to protection against soil erosion by binding soil particles with the help of enhanced calcium carbonate precipitation facilitated by the presence of biochar. Overall, this phenomenon promotes soil conservation and contributes toward the maintenance of ecological sustainability.</p>