Attachment theory categorically assesses how a person perceives and experiences interpersonal relationships. Attachment style is linked to numerous physical and psychological phenomena; however, there is a paucity of research examining its relationship to suicide ideation and attempt in adults. Our study addresses this and investigates the relationship of adult attachment style and mental disorders in a nationally representative sample. Using data from the National Comorbidity Survey Replication (N = 5692, aged >18 years), multiple logistic regression analyses were conducted to examine these relationships. After adjusting for confounding variables, insecure attachment styles were associated with greater reporting of suicidal ideation, attempt, and all mental disorder categories analyzed (adjusted odds ratio range, 1.13–1.81). Secure attachment styles were associated with a decreased likelihood of reporting suicidal ideation, attempt, and any anxiety disorder (adjusted odds ratio range, 0.67–0.91). Clinicians should be aware of attachment issues in their patients to ensure better health outcomes and more effective physician-patient relationships.