Introduction: Involuntary treatment may be a life‐saving option for extremely severe anorexia nervosa (AN) in the context of life‐threatening conditions and refusal of care. The long‐term outcomes of patients undergoing involuntary treatment for AN are poorly understood. This study aims to explore quality of life, long‐term outcomes and attitudes towards involuntary treatment in patients involuntarily treated for extremely severe AN. Methods: 23 patients involuntarily admitted for extremely severe AN (I‐AN), and 25 voluntarily admitted patients (V‐AN) were compared for body mass index (BMI), residual symptoms, quality of life, and attitudes towards treatment almost four years after discharge. In I‐AN, clinical variables were also compared between admission and follow‐up. Results: At follow‐up, weight restoration was higher in V‐AN (p = 0.01), while differences in quality of life, BMI, and mortality rates were not significant between I‐AN and V‐AN (p > 0.05). In I‐AN, BMI increased and weight‐controlling strategies decreased at follow‐up (p < 0.05). Despite negative experiences of involuntary treatment, the perception of the necessity of treatment increased from admission to follow‐up (p < 0.01) and became comparable to V‐AN (p > 0.05). Discussion: Involuntary treatment for AN does not appear to be a barrier to weight gain and clinical improvement, nor to long‐term attitudes towards treatment. Highlights: Patients with anorexia nervosa (AN) may receive involuntary treatment in cases of extreme severity and care refusal.Voluntary and involuntary patients with AN showed no significant differences in quality of life and body mass index (BMI) almost 4 years after hospitalisation.Attitudes towards treatment of involuntary patients with AN improved over time and were not significantly different from those of voluntary patients years after the acute episode. [ABSTRACT FROM AUTHOR]