Purpose: Personality functioning is strongly linked to well-being in the general population. Yet, there is a lack of scientific knowledge about the pathways between personality trait facets and emotional, psychological and social well-being in ED patients. The general aim was to examine potential associations between maladaptive personality trait facets and the three main dimensions of well-being. Methods: Participants were 1187 female eating disorder patients who were referred for specialized treatment. Patients were diagnosed with anorexia nervosa (31.7%), bulimia nervosa (21.7%), binge eating disorder (11%) and other specified eating disorders (35.5%). The Personality Inventory for the DSM 5 (PID-5) was used to measure 25 trait facets, and well-being was measured with the Mental Health Continuum Short Form (MHC-SF). Multiple hierarchical regression analyses were applied to examine potential associations between personality and well-being while controlling for background and illness characteristics. Results: Personality trait facets led to a statistically significant increase of the explained variance in emotional (38%), psychological (39%), and social well-being (26%) in addition to the background and illness characteristics. The personality trait facets anhedonia and depression were strongly associated with all three well-being dimensions. Conclusion: Personality traits may play an essential role in the experience of well-being among patients with EDs. To promote overall mental health, it may be critical for clinicians to address relevant personality trait facets, such as anhedonia and depression, associated with well-being in treatment. Level of evidence: Level V, cross-sectional descriptive study.