Aim To investigate the association between cardiovascular health (CVH) score based on life's essential 8 (LE8) on cognitive function and the mediation role of neutrophil-to-lymphocyte ratio (NLR) between them in older adults, providing basis for the prevention and control of cognitive impairment. Methods The study population was selected from the National Health and Nutrition Examination Survey (NHANES) 2011—2014 two cycles of 60 years and above, demographic characteristics, medical history and other variables were collected, the participants' CVH scores were calculated according to LE8 defined by American Heart Association, and cognitive function was assessed using the digit symbol substitution test. The relationship between CVH and cognitive function was explored using a weighted linear regression analysis, and the dose-response relationship was analyzed using a restricted cubic spline. Moreover, mediation analysis was used to explore the role of NLR in mediating the relationship between CVH score and cognitive function. Results A total of 2 510 participants were included in this study. After adjusting for relevant factors, cognitive function was positively associated with moderate CVH group score (β=3.6,5%CI:1.43~ 5.30) and high CVH group score (β=6.1,5%CI:2.89~ 9.13) compared with the low CVH group score. The LE8 single factor of diet score (β=0.4,5%CI:0.01~0.06), physical activity score (β=0.4,5%CI:0.02~0.05), tobacco exposure score (β=0.5,5%CI:0.02~0.08), blood pressure score (β=0.3,5%CI:0.01~0.05) and blood glucose score (β=0.6,5%CI:0.03~0.09) were positively correlated with cognitive function score. The results of restricted cubic splines showed that the score of CVH was linear positively correlated with the score of cognitive function. The indirect effect of CVH on cognitive function via NLR was 0.002 (P＞0.05), and the proportion of mediating effect was 1.29% (P＞0.05), indicating the mediating effect of NLR on the relationship between CVH score and cognitive function was not significant. Conclusions The CVH score based on the LE8 was positively correlated with cognitive function in older adults, underscoring the crucial role of maintaining optimal CVH levels in supporting cognitive health. However, the NLR, as an indicator of inflammation, did not exhibit a significant mediating effect between the CVH score and cognitive function. The relationship between these variables might be influenced by other mechanisms.