Expansive soils pose a significant hazard to civil engineering structures due to its high swelling and shrinkage potential. Cyclic wetting–drying phenomena can cause progressive deformation of expansive soils, which may affect building foundations, drainage channels, and liner and cover systems in waste containment facilities. Therefore, it is essential to modify these soils by stabilization techniques at the geotechnical applications. In this study, expansive soil samples were stabilized by using pine tree sawdust waste material and the effects of wetting and drying cycles on swelling behavior of stabilized expansive soils were investigated under laboratory conditions. The results indicated that conducting consecutive drying and wetting causes a considerable reduction in the swelling potential of soil samples prepared with different qualities of pore water. Consequently, it was concluded that pine tree sawdust can be successfully used to improve the swelling behaviors against the wet-dry cycle.