Background: Previous observational studies have explored the causal relationship between smoking behavior and carpal tunnel syndrome (CTS), but these studies were affected by confounding factors and yielded inconsistent results. Therefore, further exploration and validation are still required to understand the causal relationship between smoking behavior and CTS. Methods: We considered four smoking behaviors (past smoking, current smoking, smoking initiation, and never smoking) as exposures and CTS as the outcome. Two-sample Mendelian randomization analysis was employed to explore the causal relationships between these four exposures and the outcome. Exposure and outcome datasets were obtained from the IEU (Integrative Epidemiology Unit) Open genome-wide association study (GWAS) project (https:// gwas.mrcieu.ac.uk/). We conducted causal analysis using five methods (inverse-variance weighted method (IVW), weighted median method, MR Egger method, Simple mode, and weighted mode) before and after outlier exclusion. In this study, the IVW method was considered as the primary method for causal analysis. And the analysis results obtained after outlier exclusion were considered as the final results. Additionally, sensitivity analysis was performed to evaluate the robustness of the findings. Results: The analysis results revealed that current smoking (IVW: OR: 2.485, 95% CI: 1.514-4.080, P=3.184×10-4) and smoking initiation (OR: 1.362, 95% CI: 1.193-1.555, P=4.626×10-6) remained as risk factors for CTS. On the contrary, past smoking (OR: 0.753, 95% CI: 0.635-0.893, P=0.001) and never smoking (OR: 0.410, 95% CI: 0.270-0.624, P=3.056×10-5) continued to exhibit protective effects against CTS. Conclusion: Our study identified a significant association between current smoking and smoking initiation, which were found to increase the risk of CTS. Conversely, past smoking and never smoking were significantly associated with a decreased risk of CTS. These novel findings hold potential clinical significance as they can inform the development of targeted interventions for specific populations. This, in turn, can enable early prevention of CTS and facilitate timely detection and treatment for individuals with CTS.