Post-traumatic stress disorder (PTSD) and obesity are prevalent among U.S. military veterans, though less is known about the mental and physical health burden and suicidality of co-occurring PTSD and obesity in this population. A nationally representative sample of the U.S. veterans was used to assess PTSD and obesity prevalence, co-occurrence and relationships with mental and physical health measures. A total of 16.4% of veterans screened positive for current PTSD, 32.7% for obesity, and 5.8% for co-occurring PTSD and obesity. Relative to obesity-only veterans, veterans with co-occurring PTSD and obesity had elevated likelihoods of mental and physical health concerns (most notably major depressive and generalized anxiety disorders), suicidality, and migraine headaches, and higher body mass indices. Relative to veterans with PTSD alone, individuals with comorbid PTSD and obesity had elevated likelihoods of suicidal ideation, nicotine dependence, mental health treatment, migraine headaches, diabetes, hypertension, and insomnia. A significant minority of U.S. veterans has co-occurring PTSD and obesity, which is associated with substantial mental and physical health burden, including elevated suicidality. Results underscore the importance of integrative assessment, monitoring, and treatment approaches for PTSD and obesity in this population.