Background Atherosclerotic cardiovascular disease (ASCVD) results in high out‐of‐pocket healthcare expenditures predisposing to food insecurity. However, the burden and determinants of food insecurity in this population are unknown. Methods and Results Using 2013 to 2018 National Health Interview Survey data, we evaluated the prevalence and sociodemographic determinants of food insecurity among adults with ASCVD in the United States. ASCVD was defined as self‐reported diagnosis of coronary heart disease or stroke. Food security was measured using the 10‐item US Adult Food Security Survey Module. Of the 190 113 study participants aged 18 years or older, 18 442 (adjusted prevalence 8.2%) had ASCVD, representing ≈20 million US adults annually. Among adults with ASCVD, 2968 or 14.6% (weighted ≈2.9 million US adults annually) reported food insecurity compared with 9.1% among those without ASCVD ( P <0.001). Individuals with ASCVD who were younger (odds ratio [OR], 4.0 [95% CI, 2.8–5.8]), women (OR, 1.2 [1.0–1.3]), non‐Hispanic Black (OR, 2.3 [1.9–2.8]), or Hispanic (OR, 1.6 [1.2–2.0]), had private (OR, 1.8 [1.4–2.3]) or no insurance (OR, 2.3 [1.7–3.1]), were divorced/widowed/separated (OR, 1.2 [1.0–1.4]), and had low family income (OR, 4.7 [4.0–5.6]) were more likely to be food insecure. Among those with ASCVD and 6 of these high‐risk characteristics, 53.7% reported food insecurity and they had 36‐times (OR, 36.2 [22.6–57.9]) higher odds of being food insecure compared with those with ≤1 high‐risk characteristic. Conclusion About 1 in 7 US adults with ASCVD experience food insecurity, with more than 1 in 2 adults reporting food insecurity among the most vulnerable sociodemographic subgroups. There is an urgent need to address the barriers related to food security in this population.