Although studies have indicated causality between brisk walking and various diseases, the relationships between walking pace and respiratory diseases lack thorough investigation. The underlying relationships between walking pace and various respiratory diseases were examined through univariable Mendelian randomization (MR) analyses. Furthermore, we performed multivariable MR analyses to observe whether relationships between walking pace and respiratory diseases change after adjustment of body mass index (BMI). The genome-wide association study data of self-reported walking pace, BMI, and 42 respiratory diseases were retrieved from publicly available datasets. We employed the inverse-variance weighted, weighted median, and MR-Egger methods for MR analysis. Using the inverse-variance weighted method in univariable MR, we identified statistically significant negative causal associations between self-reported walking pace and 4 respiratory traits, including chronic lower respiratory diseases (odds ratio [OR], 0.27 [95% confidence interval [CI], 0.18-0.41]), asthma (OR, 0.23 [95% CI, 0.14-0.38]), chronic obstructive pulmonary disease (OR, 0.15 [95% CI, 0.08-0.30]), and diseases of the respiratory system (OR, 0.54 [95% CI, 0.41-0.70]). Similar results were observed with the MR-Egger and weighted median methods. These associations remained significant, though slightly attenuated, after adjusting for BMI. A brisk walking pace may significantly benefit respiratory health and aid in disease prevention and risk stratification.