Assessing children’s reasoning about food, including their health knowledge and their food preferences, is an important step toward understanding how health messages may influence children’s food choices. However, in many studies, assessing children’s reasoning relies on parent report or could be susceptible to social pressure from adults. To address these limitations, the present study describes the development of a food version of the Implicit Association Test (IAT). The IAT has been used to examine children’s implicit stereotypes about social groups, yet few studies have used the IAT in other domains (such as food cognition). Four- to 12-year-olds (n = 123) completed the food IAT and an explicit card sort task, in which children assessed foods based on their perception of the food’s healthfulness (healthy vs. unhealthy) and palatability (yummy vs. yucky). Surprisingly, children demonstrated positive implicit associations towards vegetables. This pattern may reflect children’s health knowledge, given that the accuracy of children’s healthfulness ratings in the card sort task positively predicted children’s food IAT d-scores. Implications for both food cognition and the IAT are discussed.