Background and aim <p>School-based nutrition education programs are commonly used to promote healthy eating behaviors among children; however, their effectiveness may vary according to developmental stage. The present study aimed to evaluate the effects of a school-based nutrition education program on children’s dietary self-efficacy (CDSS), dietary attitudes (DAS), food behaviors (FBS), and children self-rated health scale (CSHC).</p> Materials and methods <p>This study employed a pre–post nutrition intervention design and including 1418 primary and secondary school students from different grade levels. CDSS, DAS, FBS, and CSHC were assessed before and after the nutrition education using validated self-report scales. Changes following the intervention were statistically examined and differences according to grade level and gender were analyzed.</p> Results <p>Following the nutrition education program, a significant improvement was observed in child nutrition self-efficacy. In contrast, no significant overall changes were found in dietary attitudes, food behaviors, or self-rated health perception. Dietary attitudes and food behaviors differed significantly by grade level both before and after the intervention, with older children’s dietary self-efficacy and food behaviors were more evident in certain lower grade levels. No significant differences were observed between girls and boys with respect to dietary attitudes or food behaviors.</p> Conclusions <p>The findings suggest that while school-based nutrition education can enhance dietary self-efficacy, short-term educational interventions alone may be insufficient to produce measurable changes in children’s eating behaviors. Developmentally tailored, multi-component interventions that incorporate family involvement and environmental factors may be necessary to support sustained improvements in dietary behaviors, particularly among older school-age children.</p>