Observational research has shown that individuals diagnosed with rheumatoid arthritis (RA) face an elevated likelihood of developing atrial fibrillation (AF). A meta-analysis and Mendelian randomization (MR) analysis were used to explore the correlation and potential causal relationship between RA and AF. We searched PubMed, Embase, and Web of Science for cohort studies comparing AF risk among participants with and without RA. Quantitative synthesis of the adjusted risk ratio (RR) or hazards ratio was performed by the random-effects model. RA and AF were studied using a two-sample MR analysis. The Mendelian randomization (MR) analysis utilized the random-effects inverse variance weighted (IVW) method. We found patients with RA had a higher risk of AF than participants without RA [RR=1.32, 95% confidence interval (CI): 1.23-1.43, P < 0.0001]. Genetically predicted RA was not associated with a significantly higher risk of AF (odds ratio = 1.009, 95%CI: 0.986 - 1.032, P = 0.449). After adjusting for confounding factors of multifactorial MR, RA and AF still had no correlation. Sensitivity analyses yielded similar results, indicating the robustness of the causal association. Overall, RA is associated with increased risk of AF in our meta-analysis. However, genetically predicted RA may not be causal.