Alexithymia is a multidimensional personality trait consisting of difficulties labeling and describing own’s feelings and is associated with poorer treatment outcomes in patients with eating disorders. The current chapter synthesized the accumulation of knowledge from previous systematic reviews, meta-analyses, and current studies on the alexithymia’s role in clinical populations with eating disorders. Research established that alexithymia and emotion regulation difficulties are transdiagnostic characteristics across eating disorder subtypes and a new theoretical framework integrates them into the attention-appraisal model of alexithymia. The underlying mechanisms of the relationship between alexithymia and eating disorders remain unclarified, given they both have presumed complex etiology. Depression appears to have a mediation role in the relationship between alexithymia and both anorexia nervosa and binge eating, although future research should clarify the different effects of alexithymia’s facets. Although previous systematic reviews and meta-analyses indicate that alexithymia’s levels remain high even after specific treatment, recent interventions appear to be promising. Directions for future research and therapeutic implications are discussed.