With an increasing life expectancy, more octogenarian patients are referred with complex aortic aneurysms (cAAA). The aim of this study was to evaluate short and mid-term outcomes following fenestrated aortic repair (FEVAR) in octogenarians. Few studies looking at octogenarian-specific outcomes with diverging results. Retrospective, multicentre cohort study including consecutive patients undergoing elective FEVAR for cAAAs or type IV thoracoabdominal aortic aneurysms between 2007-2022 in eight high-volume centres. Octogenarians vs. non-octogenarians were compared. The primary outcome was 30-day mortality. Secondary outcomes included 1, 2 and 5-year survival and reintervention rates. A total of 729 patients (median age of 74.8 years [IQR 69.2 - 79.14]) were included, 169 (23%) of which were octogenarians, with 316 (43.3%) patients undergoing juxta/pararenal aneurysm repair. Although octogenarians presented less complex but larger (61mm vs. 58mm) aneurysms, the number of fenestrations was similar across groups. No differences in in-hospital mortality (4.1 vs. 3.0%), MAE (16.6% vs 12.2%) or reintervention rates (11.2 vs. 10%) were found. Multivariable logistic regression of in-hospital mortality identified BMI (OR 0.66, 95% CI 0.51-0.95, P=0.003), chronic heart failure (OR 7.70, 95% CI 1.36-36.15, P=0.003) and GFR<45ml/min/1.73m2 (OR 5.25, 95% CI 1.20-22.86, P=0.027) as independent predictors. Median follow-up was 41 months. The 1, 2 and 5-year survival rates were 91.3%, 81.8% and 49.5% in octogenarians vs 90.6%, 86.5% and 68.8% in non-octogenarian patients (Log-rank: =0.001). Freedom from aortic-related death and freedom from reintervention at five-years were similar across groups (log-rank=0.94 and .76, respectively). Age>80 was not an independent predictor of 30-day or long-term mortality on multivariable and Cox regression analysis. Elective FEVAR in octogenarians appears to be safe, with similar outcomes as in younger patients. Future studies looking at improved patient selection methods to ensure long-term survival benefits in both octogenarians and younger patients are warranted.