Children's eating habits are alarmingly turning towards the choice of unhealthy food, and on a daily basis, only 17% of children consume the recommended intake of vegetables. Previous literature examined children's food choice behavior by assessing only certain attitudes, therefore this paper examines the understanding of the influence of both implicit and explicit attitudes on the actual behavior of children when choosing healthy food. Also, a key factor is behavior change, so this work tests the effectiveness of interventions that encourage positive attitudes and behavior of children when choosing healthy food. For the purposes of the doctoral thesis, qualitative and quantitative research was conducted. Through qualitative research (n = 220) using the "draw and write" technique, it was established that children aged 6 and 9 know how to categorize and associate the word unhealthy with food that has a high proportion of fat and sugar. Likewise, children associate the word healthy with food such as fruits and vegetables, especially at an older age. It can be concluded that during the early years of education, it is possible to encourage children to acquire new knowledge and strengthen children's associations with the word healthy. The results of the quantitative research (n = 419) show that children who choose healthy (fruit) have more positive implicit and explicit attitudes compared to children who choose unhealthy (sweets) and that the explicit attitude has a greater influence on the choice of food than the implicit attitude. Behavioral interventions based on emotions have been shown to influence healthy food choices in younger children, while behavioral interventions based on information encourage more positive implicit attitudes in older children. Furthermore, food choice among children with weaker implicit and explicit attitudes is positively influenced by the strategy of labeling food with emoticons (cognitive intervention). As part of this work, for the first time the actual behavior of children was explained by understending their attitudes. Specifically, children who make healthy choices have more positive implicit and explicit attitudes than children who make unhealthy choices. Also, the effect of the behavioral intervention on encouraging positive attitudes was confirmed, as well as the positive effect of using emoticons on food choice, thus testing the joint effect of behavioral and cognitive digital interventions on the choice of healthy food in 6- and 9-year-old children.