New-onset atrial fibrillation (AF) is associated with adverse outcomes during a sepsis hospitalization; however, long-term outcomes following hospitalization with sepsis-associated new-onset AF are unclear.We used a Medicare 5% sample to identify patients who survived hospitalization with sepsis between 1999 and 2010. AF status was defined as no AF, prior AF, or new-onset AF based on AF claims during and prior to a sepsis hospitalization. We used competing risk models to determine 5-year risks of AF occurrence, heart failure, ischemic stroke, and mortality after the sepsis hospitalization, according to AF status during the sepsis admission.We identified 138,722 sepsis survivors, of whom 95,536 (69%) had no AF during sepsis, 33,646 (24%) had prior AF, and 9,540 (7%) had new-onset AF during sepsis. AF occurrence following sepsis hospitalization was more common among patients with new-onset AF during sepsis (54.9%) than in patients with no AF during sepsis (15.5%). Compared with patients with no AF during sepsis, those with new-onset AF during sepsis had greater 5-year risks of hospitalization for heart failure (11.2% vs 8.2%; multivariable-adjusted hazard ratio [HR], 1.25; 95% CI, 1.16-1.34), ischemic stroke (5.3% vs 4.7%; HR, 1.22; 95% CI, 1.10-1.36), and death (74.8% vs 72.1%; HR, 1.04; 95% CI,1.01-1.07).Most sepsis survivors with new-onset AF during sepsis have AF occur after discharge from the sepsis hospitalization and have increased long-term risks of heart failure, ischemic stroke, and death. Our findings may have implications for posthospitalization surveillance of patients with new-onset AF during a sepsis hospitalization.