Using industrial waste like fly ash for ground enhancement is cost-effective and environmentally sustainable. Ground enhancement serves as a practical approach for stabilizing challenging soils, such as bentonite clay, which frequently displays substantial settlement, limited resistance to shear forces, pronounced malleability, significant susceptibility to compression, dispersion, swelling, erodibility, and vulnerability to climate change. Numerous research efforts have explored the application of granular columns, particularly utilizing fly ash. Although several of these studies provided consistent statistical analyses, this research focuses on the horizontal load-bearing ability of fly ash columns within bentonite clay. The reinforced bentonite clay specimens were evaluated using various test methods, including particle size distribution analysis, plasticity index determination, compaction assessments, permeability evaluations, and unconfined compressive strength measurements. These tests were performed using single fly ash columns. The effects of varying column diameter and height were examined. The experimental results demonstrated that incorporating fly ash columns, optimized in terms of diameter, height, and confining pressure, led to a remarkable improvement in soil shear strength, with increases of up to 221.067%. This was accomplished through the effective use of a single fly ash column measuring 10 mm in diameter and 60 mm in height. The study revealed that fly ash columns greatly enhance the horizontal load-bearing capacity of bentonite clay.