In civil engineering, natural soils often lack the strength required for intended loads. Soil improvement techniques, such as using cement and fibers, are employed to bolster mechanical properties for engineering structures. This study evaluates the efficacy of cement-stabilized sand reinforced with carbon fibers under freezing and thawing cycles. Key variables investigated include cement and carbon fiber content, curing periods, and freeze-thaw cycles. Results show significant enhancements in unconfined compressive strength (UCS) with the addition of cement and carbon fibers. For instance, specimens with 10% cement and 2% carbon fiber achieved UCS values of up to 1717 kPa, 1521 kPa, and 1347 kPa under varying freeze-thaw cycles at 28 days. This combination also reduces crack formation by increasing strain at failure points. Specimens with 2% carbon fibers and 10% cement exhibited the highest failure strains under freeze-thaw cycles. However, increasing freeze-thaw cycles led to decreased UCS, although carbon fiber-reinforced specimens showed more resilience. The study highlights the efficacy of combining carbon fibers and cement for reinforcing sandy soil under freeze-thaw conditions. Cement enhances UCS during stabilization, while carbon fibers improve strain at failure, enhancing soil deformability and mitigating failure mechanisms. This research provides insights into optimizing soil stabilization methods for civil engineering projects in challenging environmental conditions. تفاصيل المقالة