OBJECTIVES The goal of this study was to describe the learning curve of an operator trained in an aortic centre during the first years of performing fenestrated/branched endovascular aortic repairs independently. METHODS Patients electively treated with fenestrated/branched stent grafts from January 2013 to March 2020 were included retrospectively. Groups were defined according to the treating operator: experienced operator (group 1), early-career operator (group 2) or both during a 14-month surgical companionship period (group 3). The early-career operator’s learning curve was assessed using a cumulative sum analysis. A composite criterion including technical failure, death and/or any major adverse event was evaluated in a logistic regression model. RESULTS Overall, 437 patients (93% male; median 69 (63, 77) years old) were included (group 1: n = 240; group 2: n = 173; group 3: n = 24). There were significantly more extended thoraco-abdominal aneurysms (extent I, II, III and V) in group 1 compared to group 2 [n = 68 (28%) vs 19 (11%), P<0.001]. The technical success rate was 94% (P=0.874). The 30-day mortality and/or major adverse event rates in juxta-/pararenal aneurysms or extent IV thoraco-abdominal aneurysms were 8.1% in group 1 and 9.7% in group 2 (P = 0.612), whereas they were 10% (group 1) and 0 (group 2) for extended thoraco-abdominal aneurysms (P=0.339). The adjusted cumulative sum analysis highlighted satisfactory results from the beginning of the experience. The operator’s experience was not predictive of the composite criterion [adjusted OR 0.77; 95% (0.42, 1.40); P=0.40]. CONCLUSIONS This study demonstrated favourable outcomes in patients treated with a fenestrated/branched aortic stent graft performed by an early-career operator trained in a high-volume centre from the beginning of independent practice.