The relationship between firearm violence and mental illness has been a longstanding issue, and one that has received recent national attention due to highly publicized shootings. However, no prior reviews have focused on the relationship between firearm violence and posttraumatic stress disorder (PTSD) specifically. The current review examines evidence of PTSD as both a consequence of and risk factor for firearm violence. The studies reviewed suggest elevated rates of PTSD among those exposed to firearm violence, with particularly high levels of PTSD found among witnesses of mass shootings and firearm injury survivors. Additionally, these studies indicate that certain factors, such as closer proximity to the incident and closer relationship to the victims, increase one's risk for developing PTSD. Although there is a dearth of research on PTSD as a risk factor for perpetration of firearm violence, the available evidence suggests a significant connection between the two. Gaps in the current literature are discussed, as well as directions for future study. Firearm violence remains a significant public health concern, and identifying its impacts and potential risk factors such as PTSD will be crucial for interventions aimed at addressing this problem.