Objective: This study sought to analyse the effectiveness of a nurse-led health development programme for school-aged children in North Cyprus. Design: This study utilised a randomised-controlled experimental research design. Setting: The study was conducted on fourth-grade students in two primary schools. Method: Participants in the intervention group received a 12-week online health education course. Students in both the control (n = 38) and intervention (n = 38) groups completed the Food Behaviour Scale, the Children Health Perceptions and Behaviours Scale, and the Physical Activity Self-Efficacy Scale pre-intervention, at the end of intervention and 3 months post-intervention. Results: Post-test scores for the intervention group on the Food Behaviour Scale, Children Health Perceptions and Behaviours Scale, and Physical Activity Self-Efficacy Scale were significantly higher than their pre-test scores. In contrast, the control group exhibited no statistically significant difference between the pre- and post-test scores on the three scales. Conclusion: The findings suggest that a nurse-led health education programme had a positive effect on food behaviour, physical activity self-efficacy, and health perception and behaviours among school-age children.