Black cotton soil, known for its expansive properties, presents significant challenges for construction due to its high swelling and shrinkage behaviour. This study investigates the stabilisation of black cotton soil using varying proportions of fly ash and bagasse ash. Black cotton soil samples collected from Gujarat were treated with different combinations of fly ash (FA) and bagasse ash (BA) to evaluate improvements in geotechnical properties. The study revealed that the addition of 8% fly ash and 2% bagasse ash resulted in the lowest liquid limit of 66%, while the combination of 6% fly ash and 8% bagasse ash achieved the lowest plastic limit of 25%. The optimum moisture content (OMC) decreased to 27% upon the addition of admixtures, with the maximum dry density (MDD) reducing to 1.48 g/cc at 6% fly ash and 8% bagasse ash. The California Bearing Ratio (CBR) value increased significantly, indicating improved load-bearing capacity. The specific gravity of the treated soil decreased to 2.21 with the combination of 8% bagasse ash and 2% fly ash. These findings demonstrate the effectiveness of fly ash and bagasse ash in enhancing the stability and suitability of black cotton soil for construction applications, providing a sustainable and cost-effective solution.