The study examined the behavioural intention to adopt climate-smart agricultural practices (CSA) and its impact on the food-nutrition security (FNS) of farming households in South Africa. We employed a multistage sampling procedure to select rural maize farmers across the selected villages. To determine the impacts of behavioural adoption of CSA on the FNS of farming households, endogenous switching regression model (ESRM) was employed, while household dietary diversity score (HDDS) and household food insecurity access score (HFIAS) were used to determine the FNS status of the households. The findings emphasized the significance of the behavioural intentions of rural maize farmers, assessed through their attitudinal dimensions (measured in terms of perceived social norms, behavioural intentions, and control) in influencing the adoption decision of CSA practices, hence CSA adoption positively impacts FNS in South Africa. The result indicates that households that adopt CSA observe a 27% and 23% increase in HDDS and a decrease in HFIAS compared to those who do not adopt CSA practices, respectively. Thus, the outcome illustrates that the adoption of CSA practices substantially enhances the HDDS and HFIAS of rural maize farming households in South Africa. Following this backdrop, a concerted effort to raise knowledge of CSA practices through disseminating pertinent information will exert influence on the farmers' adoption behaviour towards CSA practices, which is capable of improving the FNS of rural maize farmers.