Abstract Background The American Heart Association’s Life’s Essential 8 (LE8) score is a helpful tool to quantify cardiovascular health (CVH) metrics. Sex differences in relation to LE8 and its association with mortality are not known. Methods The National Health and Nutrition Examination Survey (NHANES) between 2009 and 2018 was utilized to evaluate the prevalence of health metrics included in LE8 among adult patients, stratified by sex. Health metrics were further subdivided into health behaviors (diet, physical activity, nicotine exposure, and sleep) and health factors (body mass index, non–high density lipoprotein cholesterol, blood glucose, and blood pressure). LE8 scores were also evaluated based on age, race/ethnicity, and socioeconomic status. Cox proportional hazard models were used to evaluate the association between the levels of CVH and risk of all-cause and cardiovascular mortality. Results Among 22,761 participants, 52% were female. Overall CVH score was similar in both females and males (65.8 vs. 65.9). Females had higher health factors score (64.3 vs. 63.1, p <0.001) and lower health behaviors score (67.2 vs 68.6, p <0.001). Amongst individual metrics, blood pressure score was higher in females (73.2 vs. 67.7, p <0.001) while males had higher physical activity score (70.6 vs. 54.9, p <0.001). For individuals under 65 years of age, overall CVH and health factors scores were higher in females while in those age 65 or older, males had higher scores. The most prominent sex differences were noted in non-Hispanic Black females who had significantly lower CVH scores than Black males. High or moderate LE8 scores vs. low LE8 scores demonstrated lower all-cause and CV mortality in both sexes (p-interaction 0.98 and 0.9). High or moderate health behaviors scores also demonstrated a significant association with lower all-cause and CV mortality, with the reduction in mortality being more prominent in females (p-interaction 0.01 and 0.03). Conclusions We demonstrate important sex differences in CVH metrics along with notable variations based on age and race/ethnicity. Furthermore, we highlight sex differences in the association of CVH metrics with mortality. These findings underscore the importance of designing and implementing effective strategies for both sexes, aimed at targeting these specific factors.