Objectives. To document the increasing influence of firearm suicide on the incidence of traumatic brain injury (TBI)-related death in the United States.Methods. We used national vital statistics data from 2008 to 2017 to identify TBI-related deaths, overall and by cause, among US residents. National counts stratified by year, sex, and age group (to facilitate age adjustment) were merged with corresponding population estimates to calculate incidence rates.Results. During the 10-year period beginning in 2008, when it became the leading cause of TBI-related death in the United States, firearm suicide accounted for nearly half (48.3%) of the increase in the absolute incidence of TBI-related death when combining all injury categories showing absolute increases. Rates of TBI-related firearm suicide increased among both males and females.Conclusions. Safe storage of firearms among people at risk and training of health care providers and community members to identify and support people who may be thinking of suicide are part of a comprehensive public health approach to suicide prevention.Public Health Implications. States, communities, and health care systems can save lives by prioritizing comprehensive suicide prevention.