Objective: The objective of this study was to evaluate the association of statin use after coronary artery bypass grafting (CABG) and long-term adverse events in a large population-based, nationwide cohort. Methods: All 35,193 patients who underwent first-time isolated CABG in Sweden from 2006 to 2017 and survived at least 6 months after surgery were included. Individual patient data from the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) and 4 other nationwide registries were merged. Multivariable Cox regression models adjusted for age, sex, comorbidities, and time-updated treatment with other secondary preventive medications were used to evaluate the associations between statin treatment and outcomes. The primary end point was major adverse cardiovascular events (MACE). Median follow-up time to MACE was 5.3 (interquartile range, 2.5-8.2) years. Results: Statins were dispensed to 95.7% of the patients six months after discharge and to 78.9% after 10 years. At baseline, 1.4% of patients were prescribed low-, 57.6% intermediate-, and 36.7% high-dose statins. Ongoing statin treatment was associated with markedly reduced risk of MACE (adjusted hazard ratio [aHR], 0.56 [95% CI, 0.53-0.59]), all-cause mortality (aHR, 0.53 [95% CI, 0.50-0.56]), cardiovascular death (aHR, 0.54 [95% CI, 0.50-0.59]), myocardial infarction (aHR, 0.61 [95% CI, 0.55-0.69]), stroke (aHR, 0.66 [95% CI, 0.59-0.73]), new revascularization (aHR, 0.79 [95% CI, 0.70-0.88]), new angiography (aHR, 0.81 [95% CI, 0.74-0.88]), and dementia (aHR, 0.74 [95% CI, 0.65-0.85]; all P <.01), irrespective of the statin dose. Conclusions: Ongoing statin use was associated with a markedly reduced incidence of adverse events and mortality after CABG. Initiating and maintaining statin medication is essential in CABG patients.