Introduction Cannabinoid users are at high risk of developing atrial arrhythmias. We sought to investigate the outcomes and the economic impact of marijuana use on patients with atrial fibrillation utilizing the National Inpatient Sample. Materials and Methods Patients with atrial fibrillation were identified in the National Inpatient Sample (NIS) database between 2012 and 2014 using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), who subsequently were divided into two groups, those with and without marijuana smoking. The primary outcome was all-cause in-hospital mortality in the two groups. Secondary outcomes were in-hospital morbidities, required procedures and complications. We also evaluated the length of hospital stay and the cost of hospitalization. Logistic regression model was performed to address potential confounding factors. Results: The marijuana-users group had no significant increase of in-hospital mortality (OR: 1.24; 95% CI: 0.51 - 3.01, p = 0.632). However, marijuana users were predominantly younger males and less likely to undergo cardiac surgery (OR: 0.54, 95% CI 0.37 - 0.78, p = 0.001). Moreover, marijuana users are more likely to have a lower cost of hospitalization when compared to non-users ($28,916 vs $32,303, p = 0.001). Conclusion: Cannabinoid use was not associated with an increase in mortality among patients admitted with atrial fibrillation. However, marijuana users were younger, had fewer comorbidities, and cardiac surgeries with associated lower hospitalization costs. Admittedly, given the growing popularity of these products, further large prospective studies are needed to investigate the safety and evaluate different integral associations of cannabis use with worse cardiac outcomes in atrial arrhythmias patients, particularly those with atrial fibrillation.