Food selectivity is common among children with autism spectrum disorder (ASD), and repeated exposure to food is considered a key component of treating this problem. This study investigated the effects of a preventive program using repeated exposure of vegetables on vegetable consumption, both in an experimental setting and during mealtime among preschoolers with ASD showing no severe food selectivity. A total of 27 preschoolers with ASD were assigned to either a 6-month-long exposure program (n = 13, mean age = 4.42 years) or a control group (n = 14, mean age = 4.04 years). The training program was developed to facilitate visual and tactile contact with various vegetables and consisted of 24 activities, which were repeated four times using different vegetables. The training was conducted four times a week at the children’s early intervention agency by their therapists. Changes in vegetable consumption in the experimental setting as well as nutritional intake during regular mealtime were compared between the exposure and control groups, before and after the exposure program. Significant group differences were found in vegetable consumption, but not in nutritional intake during regular mealtime. The limitations and direction for future research are further discussed.