Background Socioeconomic factors may lead to a disproportionate impact on health care usage and death among individuals with congenital heart defects (CHD) by race, ethnicity, and socioeconomic factors. How neighborhood poverty affects racial and ethnic disparities in health care usage and death among individuals with CHD across the life span is not well described. Methods and Results Individuals aged 1 to 64 years, with at least 1 CHD‐related International Classification of Diseases, Ninth Revision, Clinical Modification ( ICD‐9‐CM ) code were identified from health care encounters between January 1, 2011, and December 31, 2013, from 4 US sites. Residence was classified into lower‐ or higher‐poverty neighborhoods on the basis of zip code tabulation area from the 2014 American Community Survey 5‐year estimates. Multivariable logistic regression models, adjusting for site, sex, CHD anatomic severity, and insurance‐evaluated associations between race and ethnicity, and health care usage and death, stratified by neighborhood poverty. Of 31 542 individuals, 22.2% were non‐Hispanic Black and 17.0% Hispanic. In high‐poverty neighborhoods, non‐Hispanic Black (44.4%) and Hispanic (47.7%) individuals, respectively, were more likely to be hospitalized (adjusted odds ratio [aOR], 1.2 [95% CI, 1.1–1.3]; and aOR, 1.3 [95% CI, 1.2–1.5]) and have emergency department visits (aOR, 1.3 [95% CI, 1.2–1.5] and aOR, 1.8 [95% CI, 1.5–2.0]) compared with non‐Hispanic White individuals. In high poverty neighborhoods, non‐Hispanic Black individuals with CHD had 1.7 times the odds of death compared with non‐Hispanic White individuals in high‐poverty neighborhoods (95% CI, 1.1–2.7). Racial and ethnic disparities in health care usage were similar in low‐poverty neighborhoods, but disparities in death were attenuated (aOR for non‐Hispanic Black, 1.2 [95% CI=0.9–1.7]). Conclusions Racial and ethnic disparities in health care usage were found among individuals with CHD in low‐ and high‐poverty neighborhoods, but mortality disparities were larger in high‐poverty neighborhoods. Understanding individual‐ and community‐level social determinants of health, including access to health care, may help address racial and ethnic inequities in health care usage and death among individuals with CHD.