Importance: Traumatic brain injury (TBI) was common among US service members deployed to Iraq and Afghanistan. Although there is some evidence to suggest that TBI increases the risk of cardiovascular disease (CVD), prior reports were predominantly limited to cerebrovascular outcomes. The potential association of TBI with CVD has not been comprehensively examined in post-9/11-era veterans. Objective: To determine the association between TBI and subsequent CVD in post-9/11-era veterans. Design, Setting, and Participants: This was a retrospective cohort study conducted from October 1, 1999, to September 30, 2016. Participants were followed up until December 31, 2018. Included in the study were administrative data from the US Department of Veterans Affairs and the Department of Defense from the Long-term Impact of Military-Relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium. Participants were excluded if dates did not overlap with the study period. Data analysis was conducted between November 22, 2021, and June 28, 2022. Exposures: History of TBI as measured by diagnosis in health care records. Main Outcomes and Measures: Composite end point of CVD: coronary artery disease, stroke, peripheral artery disease, and cardiovascular death. Results: Of the 2530875 veterans from the consortium, after exclusions, a total of 1559928 veterans were included in the analysis. A total of 301169 veterans (19.3%; median [IQR] age, 27 [23-34] years; 265217 male participants [88.1]) with a TBI history and 1258759 veterans (80.7%; median [IQR] age, 29 [24-39] years; 1012159 male participants [80.4%]) without a TBI history were included for analysis. Participants were predominately young (1058054 [67.8%] <35 years at index date) and male (1277376 [81.9%]). Compared with participants without a history of TBI, diagnoses of mild TBI (hazard ratio [HR], 1.62; 95% CI, 1.58-1.66; P <.001), moderate to severe TBI (HR, 2.63; 95% CI, 2.51-2.76; P <.001), and penetrating TBI (HR, 4.60; 95% CI, 4.26-4.96; P <.001) were associated with CVD in adjusted models. In analyses of secondary outcomes, all severities of TBI were associated with the individual components of the composite outcome except penetrating TBI and CVD death. Conclusions and Relevance: Results of this cohort study suggest that US veterans with a TBI history were more likely to develop CVD compared with veterans without a TBI history. Given the relatively young age of the cohort, these results suggest that there may be an increased burden of CVD as these veterans age and develop other CVD risk factors. Future studies are needed to determine if the increased risk associated with TBI is modifiable..