Background The impact of new-onset postoperative atrial fibrillation (POAF) on long-term outcomes of patients after non-cardiac surgery remains controversial. Here we report the 3-year follow-up of a previous case-control study to determine the relationship between new-onset POAF and long-term outcomes in patients after non-cardiac surgery. Methods In a previous case-control study, 213 patients who were admitted to the intensive care unit (ICU) after non-cardiac surgery were included; of them 71 were in the POAF group and 142 the control group. A telephone interview was performed with patients or their family members at 3 years after surgery. The primary endpoint was the incidence of major adverse cardiovascular events (MACEs) within 3 years, including cardiovascular death, non-fatal cardiac arrest, acute myocardial infarction, congestive heart failure, and ischemic stroke. A logistic regression model was established to assess the association between the occurrence of new-onset POAF and the development of 3-year MACEs. Results 202 patients completed the 3-year follow-up and were included in the analysis; of them 68 were in the POAF group and 134 were in the control group. The incidence of 3-year MACEs was higher in the POAF group than in the control group (64.7% [44/68] vs. 23.1% [31/134], p<0.001). After correction for confounding factors, new-onset POAF was independently associated with an increased risk of 3-year MACEs (odds ratio 5.448, 95% confidence interval 2.202-13.481, p<0.001). Conclusions For adult patients admitted to the ICU after non-cardiac surgery, new-onset POAF was an independent risk factor for the development of MACEs within 3 years.