BACKGROUND: The association of historical redlining policies, a marker of structural racism, with contemporary heart failure (HF) risk among White and Black individuals is not well established. METHODS: We aimed to evaluate the association of redlining with the risk of HF among White and Black Medicare beneficiaries. Zip code-level redlining was determined by the proportion of historically redlined areas using the Mapping Inequality Project within each zip code. The association between higher zip code redlining proportion (quartile 4 versus quartiles 1-3) and HF risk were assessed separately among White and Black Medicare beneficiaries using generalized linear mixed models adjusted for potential confounders, including measures of the zip code-level Social Deprivation Index. RESULTS: A total of 2 388 955 Medicare beneficiaries (Black n=801 452; White n=1 587 503; mean age, 71 years; men, 44.6%) were included. Among Black beneficiaries, living in zip codes with higher redlining proportion (quartile 4 versus quartiles 1-3) was associated with increased risk of HF after adjusting for age, sex, and comorbidities (risk ratio, 1.08 [95% CI, 1.04-1.12]; P<0.001). This association remained significant after further adjustment for area-level Social Deprivation Index (risk ratio, 1.04 [95% CI, 1.002-1.08]; P=0.04). A significant interaction was observed between redlining proportion and Social Deprivation Index (Pinteraction<0.01) such that higher redlining proportion was significantly associated with HF risk only among socioeconomically distressed regions (above the median Social Deprivation Index). Among White beneficiaries, redlining was associated with a lower risk of HF after adjustment for age, sex, and comorbidities (risk ratio, 0.94 [95% CI, 0.89-0.99]; P=0.02). CONCLUSIONS: Historical redlining is associated with an increased risk of HF among Black patients. Contemporary zip code-level social determinants of health modify the relationship between redlining and HF risk, with the strongest relationship between redlining and HF observed in the most socioeconomically disadvantaged communities.