Food insecurity, a social and economic condition of limited availability of healthy food, is a risk factor for adverse cardiovascular health outcomes among adults; few studies have been conducted in adolescents. This study explores the association between food insecurity and cardiovascular health risk factors among a nationally representative sample of US adolescents, adopting the American Heart Association's Life's Essential 8 metric. We analyzed data from 2534 adolescents aged 12 to 19 years from the 2013 to 2018 National Health and Nutrition Examination Surveys. In the sample, 24.8% of adolescents lived in food-insecure households. After multivariable adjustment, food insecurity was associated with a 3.23-unit lower total Life's Essential 8 score (95% CI, -6.32, -0.15) and lower scores on diet quality (β=-5.39 [95% CI, -8.91, -1.87]) and nicotine exposure (β=-4.85 [95% CI, -9.24, -0.45]). Regarding diet, food insecurity was associated with 5% lower Healthy Eating Index-2015 scores [95% CI, -7%, -2%], particularly lower intakes of whole grains and seafood/plant proteins and marginally higher intake of added sugar. Regarding nicotine exposure, food insecurity was associated with ever use of a tobacco product among m (odds ratio, 1.74 [95% CI, 1.20-2.53]). Compared with their food-secure counterparts, food-insecure male (odds ratio, 1.98 [95% CI, 1.07-3.65]) and female (odds ratio, 3.22 [95% CI, 1.60-6.45]) adolescents had higher odds of living with a current indoor smoker. In this nationally representative sample of adolescents, food insecurity was associated with multiple indicators of cardiovascular health risk. These findings underscore the need for public health interventions and policies to reduce food insecurity and improve cardioprotective behaviors during adolescence, with particular efforts targeting diet quality and nicotine exposure.