Background Combat exposure is associated with increased risk of mental disorders and suicidality. Moral injury, or persistent effects of perpetrating or witnessing acts that violate one's moral code, may contribute to mental health problems following military service. The pervasiveness of potentially morally injurious events (PMIEs) among U.S. combat veterans, and what factors are associated with PMIEs in this population remains unknown. Methods Data were analyzed from the National Health and Resilience in Veterans Study (NHRVS), a contemporary and nationally representative survey of a population‐based sample of U.S. veterans, including 564 combat veterans, collected September–October 2013. Types of PMIEs (transgressions by self, transgressions by others, and betrayal) were assessed using the Moral Injury Events Scale. Psychiatric and functional outcomes were assessed using established measures. Results A total of 10.8% of combat veterans acknowledged transgressions by self, 25.5% endorsed transgressions by others, and 25.5% endorsed betrayal. PMIEs were moderately positively associated with combat severity (β = .23, P < .001) and negatively associated with white race, college education, and higher income (βs = .11–.16, Ps < .05). Transgressions by self were associated with current mental disorders (OR = 1.65, P < .001) and suicidal ideation (OR = 1.67, P < .001); betrayal was associated with postdeployment suicide attempts (OR = 1.99, P < .05), even after conservative adjustment for covariates, including combat severity. Conclusions A significant minority of U.S combat veterans report PMIEs related to their military service. PMIEs are associated with risk for mental disorders and suicidality, even after adjustment for sociodemographic variables, trauma and combat exposure histories, and past psychiatric disorders.