The increasing land value and limited availability of suitable construction sites force engineers to construct buildings in soft, cohesive soils. However, buildings in such deposits face excessive settlement and stability problems. Stone columns are vertical rigid inclusions in cohesive soil that can enhance soft soil properties by reducing the settlement and increasing the bearing capacity. Depletion of natural resources forces engineers to construct stone columns using recycled materials for sustainable development. Construction and demolition waste (CDW) is one such alternative material available in the market. This paper studies the effectiveness of different diameters of single-stone columns made of crushed stone aggregate (CSA) and CDW in improving the load-carrying capacity of black cotton soil (BCS). The results showed that reinforcing the soft soil with a single-stone column enhances the load-carrying capacity to a maximum of 1.8 times its initial value. The load-bearing capacity showed an improvement with the increase in the diameter of the column. The suitability of replacing natural aggregate with CDW was also checked for different diameters. Even though the performance of the stone columns filled with CDW was slightly lower than that made of natural aggregate, it showed a significant enhancement compared to the load-carrying capacity of unreinforced soft soil. Thus, the results indicated the viability of replacing CDW with natural aggregate in stone columns for sustainable ground improvement of soft soil.