Objective Attachment insecurity and emotional competences (EC) form a key part of conceptual models of anorexia nervosa (AN). We explored the relationship between attachment dimensions and EC on the severity of eating disorders in patients diagnosed with restrictive AN. Method Sixty‐three female patients with restrictive AN and 63 healthy participants completed self‐report measures (eating symptoms, EC, attachment, depression, and anxiety). Result Patients with restrictive AN used fewer adaptive and more maladaptive regulation strategies and showed low levels of intrapersonal EC. The partial least squares path modeling analysis showed that high levels of attachment anxiety or avoidance lead to a decrease in intrapersonal EC, which in turn contributes to greater severity of eating symptoms in anorexic patients. Conclusions Lower intrapersonal EC played an important mediating role in the effects of attachment insecurity on the severity of eating disorders. The joint use of therapeutic programs that target both EC and attachment processes constitutes a promising approach.