Research has shown that posttraumatic stress disorder (PTSD), substance use disorder (SUD), criminality, and violence are powerfully intertwined. However, little is known about the prevalence of violence perpetration amongst individuals with co-occurring PTSD and SUD (PTSD + SUD) and how such histories impact and interact with varying treatment approaches. The present study examined the rates and effect upon treatment of violent offenses in individuals with PTSD + SUD. We analyzed psychiatric, legal, and demographic data of an ethnically diverse sample (n = 80) recruited from an urban, economically disadvantaged area to participate in a randomized controlled trial of two cognitive behavioral treatments for PTSD + SUD: Concurrent Treatment of PTSD and SUD Using Prolonged Exposure (COPE) and Relapse Prevention (RP). A majority of the sample (61.3%) endorsed a prior arrest history; 27.5% of individuals reported an arrest for a violent crime with men disproportionately represented among those with a violent offending history (60.3% vs.90.9%, p = .008). Two-level mixed effect models revealed an interaction between violent offending, treatment type, and time upon PTSD symptom severity, but not SUD symptom severity. Findings underscore the likelihood of criminal justice involvement among individuals suffering from PTSD + SUD and the relevance of trauma-informed care to justice-involved populations. Treatment which targets PTSD and SUD concurrently, in contrast to SUD-only interventions, may be particularly beneficial for individuals with histories of violence perpetration, suggesting a potential avenue for breaking cycles of victimization and violence.