Military suicide prevention and control has become a priority to military authorities due to its increasing rates and consequences. However, there is still paucity of research examining associated factors that put veterans at risk for suicidal attempts. This study examined association between moral injury, mental health outcomes, contextual factors (pre-deployment ideation, post-deployment duration) and suicidal attempts by rank in Nigerian military veterans. A total of 582 purposively sampled military veterans who were exposed to insurgency completed a cross-sectional survey and standardised instruments were utilised to assess study variables. To examine associations of exposure to potentially morally injurious events (PMIEs; witnessing, perpetrating, and betrayal), control variables and suicidal attempts, we estimated two series of multivariable binary logistic regressions stratified by rank, with suicide attempt as the dependent variable. Results indicated that potentially morally injurious events, particularly due to perpetration was the greatest risk factor for suicidal attempts for both enlisted and officers. Enlisted veterans who reported perpetration (OR1.9, 95%CI; 1.1-2.8) and betrayal (OR-1.7,95%CI; 1.2-2.6) were more likely to report suicidal attempts than those who denied perpetration and betrayal. Witnessing morally injurious events emerged as a significant risk factor for suicidal attempts in military officers (AOR = 1.54, 95% CI 1.2-1.8) but not in the enlisted veterans. The fully adjusted model revealed no significant association between moral injury due to betrayal and suicide attempts after post-deployment other factors were controlled. Military authorities should give more attention to moral injury when assessing and designing intervention for suicide prevention, especially among enlisted veterans.