Objective Research suggests that the way anger is expressed and efforts to control anger may be particularly important in post‐traumatic stress disorder (PTSD). However, factors influencing the association between PTSD symptom severity and anger expression and control, and whether these associations are influenced in part by cognitive processes, have yet to be investigated in combat veterans. The aim of the present study was to investigate the mediating effect of trauma‐related cognitive variables between combat‐PTSD symptom severity and anger expression in Australian veterans. Method A sample of 149 treatment‐seeking Australian older‐aged veterans with chronic combat‐related PTSD completed a battery of measures that assessed combat‐PTSD symptom severity, anger indices, trauma‐related rumination, cognitive suppression, and trauma appraisals. Results Path analyses revealed that negative beliefs about self partially mediated the effect of PTSD symptom severity and anger suppression, and PTSD symptom severity and anger control, while negative beliefs about the world partially mediated the association between PTSD severity and outward expression of anger. A significant direct effect from combat‐PTSD symptom severity to outward expression was also found. Conclusions Findings lend support to targeted assessment and treatment of negative trauma‐related appraisals, particularly negative beliefs about self and the world, to concomitantly enhance anger coping and emotion regulation in middle‐ to older‐aged veterans with chronic combat‐related PTSD.