This study investigates the association between osteoarthritis (OA) and hypertension using observational data and Mendelian randomization (MR) analysis. The study analyzed data from the National Health and Nutrition Examination Survey (NHANES) spanning 2013–2020, including 24,871 participants. Observational analysis found no significant association between OA and hypertension after adjusting for confounding factors, although a higher risk of hypertension was observed in males with OA. MR analysis, which uses genetic variants as instruments to infer causality, did not find any causal relationship between OA and hypertension across various OA phenotypes, including knee OA, hip OA, and OA from the UK Biobank. These findings were consistent across genders and in both directions of MR analysis. The study concludes that while observational data suggest a higher risk of hypertension in males with OA, MR analysis does not support a causal link between OA and hypertension. The study highlights the need for further research to clarify the potential relationship between OA and hypertension, particularly in males. The results indicate that current evidence does not support a causal relationship between OA and hypertension, and that observational findings may be influenced by confounding factors. The study also emphasizes the importance of using larger genetic datasets for future MR analyses to better understand the potential causal relationship between OA and hypertension.This study investigates the association between osteoarthritis (OA) and hypertension using observational data and Mendelian randomization (MR) analysis. The study analyzed data from the National Health and Nutrition Examination Survey (NHANES) spanning 2013–2020, including 24,871 participants. Observational analysis found no significant association between OA and hypertension after adjusting for confounding factors, although a higher risk of hypertension was observed in males with OA. MR analysis, which uses genetic variants as instruments to infer causality, did not find any causal relationship between OA and hypertension across various OA phenotypes, including knee OA, hip OA, and OA from the UK Biobank. These findings were consistent across genders and in both directions of MR analysis. The study concludes that while observational data suggest a higher risk of hypertension in males with OA, MR analysis does not support a causal link between OA and hypertension. The study highlights the need for further research to clarify the potential relationship between OA and hypertension, particularly in males. The results indicate that current evidence does not support a causal relationship between OA and hypertension, and that observational findings may be influenced by confounding factors. The study also emphasizes the importance of using larger genetic datasets for future MR analyses to better understand the potential causal relationship between OA and hypertension.