Summary Objective To identify predictors of hypothalamic‐pituitary‐adrenal ( HPA ) axis recovery interval and severity of glucocorticoid withdrawal symptoms ( GWS ) in patients undergoing adrenalectomy for corticotropin‐independent cortisol excess. Design This is a retrospective study of patients with mild autonomous cortisol excess ( MACE ), moderate and severe Cushing syndrome ( CS ) who developed adrenal insufficiency after unilateral adrenalectomy between 1998 and 2017. Results Adrenalectomy was performed in 81 patients (79% women, median age 52 years [ IQR 42‐62]). HPA axis recovery occurred at a median of 4.3 months ( IQR 1.6‐11.4) after adrenalectomy (severe CS vs moderate CS vs MACE : median 11.4 vs 2.8 vs 2.1 months, P < 0.01). Main predictors of HPA axis recovery interval included: preoperative serum cortisol concentration after 1‐mg overnight dexamethasone suppression test >10 μg/ dL or >276 nmol/L (9.7 vs 1.3 months if cortisol ≤10 μg/ dL or ≤276 nmol/L, P < 0.01); body mass index (for every 3 kg/m 2 decrease, glucocorticoid taper increased by 1 month, P < 0.05); age <45 (11.4 vs 2.3 months if ≥45 years, P < 0.05); duration of symptoms prior to diagnosis >1 year (11.4 vs 2.8 months if ≤1 year); moon facies (11.4 vs 2.2 months if no rounding of the face); and myopathy (13.1 vs 2.7 months if no myopathy, P < 0.05). Patients with severe CS had a higher incidence of GWS compared to patients with MACE (66.7% vs 40.0%, P < 0.05) with a median of 1 and 0 events/patient, respectively. Conclusions The HPA axis recovery interval was the longest for patients with severe CS . Surprisingly, patients with moderate CS recovered their HPA axis as quickly as those with MACE . Glucocorticoid withdrawal symptoms were observed in all groups, with more events in patients with severe CS . This study emphasizes the need to counsel patients on expectations for HPA axis recovery and address intervention for GWS based on individual preoperative parameters.