Background: Early childhood is a crucial developmental period whereby children acquire nutrition knowledge and skills, presenting a significant potential for lifestyle interventions. This study aimed to assess the effects of a nutrition intervention on knowledge and food choice behavior among preschool students. Methods: A semi-experimental, pre-post design study was conducted with 45 children (20 girls and 25 boys) aged 60–72 months, preschool students. Students participated in a 4-week nutrition education. The researchers carried out a pre- and post-intervention evaluation of a nutrition education intervention, employing age-appropriate visual food cards, a plate icon, and a traffic light icon. A questionnaire was used to collect data, and anthropometric measurements of children were recorded. Data were analyzed using IBM SPSS Statistics 26.0. Paired t-tests were applied for quantitative variables and the McNemar test for categorical variables. Statistical significance was set at p < 0.05. Results: The mean age of preschool children was 61.8 ± 4.40 months. Based on BMI for age z-score classification in children, more than half of the children are of normal weight (51.1%), while 22.2% are underweight and 26.7% are overweight or obese. The total mean NutriSTEP® score for preschool children before intervention was 22.9 ± 5.82. After nutrition education, preschool students significantly improved MyPlate knowledge and healthy and unhealthy food choice behaviors (p < 0.001). Conclusions: Nutrition education intervention has been shown to be effective in identifying food types and differentiating between healthy and unhealthy food among preschool children. The use of food cards and visual materials can be a valid strategy for determining the effectiveness of nutrition education. Developing financially accessible, plausible, and culturally pertinent methods to enhance student health through nutrition education may augment preschool students’ knowledge and healthy choice of foods.