ABSTRACT Expansive soils are considered problematic for civil engineering applications due to their low strength, high compressibility, and poor bearing capacity, which limit their use as foundation or pavement subgrade materials. To overcome these limitations, this study investigates the stabilization of expansive soil using gypsum and Microbially Induced Calcite Precipitation (MICP) as strengthening agents. The experimental program was carried out in three stages. In the first stage, gypsum, an industrial by-product, was incorporated into the soil in varying proportions of 2%, 4%, 6%, 8%, and 10% by dry weight. The treated samples were tested for Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). The results revealed a significant improvement in strength with increasing gypsum content up to 4%, beyond which a slight reduction was observed. Thus, 4% gypsum was identified as the optimum content for stabilization. In the second stage, MICP treatment was applied by introducing bacterial solutions in concentrations of 2 ml, 4 ml, 6 ml, 8 ml, and 10 ml under optimum moisture conditions. The treated samples were tested for Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). The results revealed a significant improvement in strength with increasing MICP content up to 4ml-MICP, beyond which a slight reduction was observed. Thus, 4ml-MICP was identified as the optimum content for stabilization. In the final stage, 4% gypsum and MICP (4 ml MICP concentration) were combined and applied to new soil samples to evaluate the combined effect on strength enhancement. However, the results showed a decrease in strength in the UCS test. The comparative analysis indicated that the individual treatments performed better depending on the curing period. Overall, the study demonstrates that gypsum provides a more sustainable improvement when compared to MICP, whereas MICP offers a more cost-effective solution. Both gypsum and MICP are environmentally friendly stabilizers suitable for enhancing the performance of expansive soils in geotechnical and pavement applications