Background: Overweight among school children become a significant public health concern in both developing and developed countries, as it is accompanied by numerous health problems. The aim of this study was to evaluate the effect of Health Belief Model on lifestyle among overweight secondary school female students. Research design: A quasi-experimental design was used. Setting: This study was carried out at governmental secondary schools at El Sharabia District in North Cairo Governorate. Sampling: A purposive sample of 82 overweight secondary school female students. Two tools were used: A self-administered questionnaire for the secondary school female students included; demographic characteristics, knowledge regarding overweight, and lifestyle aspects. The second tool was health belief model Results:  This study revealed that there are highly statistically significant differences (p < 0.001) between total satisfactory knowledge, and total lifestyle aspects as dietary habits, food frequency consumption, physical activities, and sleeping pattern among overweight secondary school female students pre/post implementation of health belief model. There is a highly statistically significant difference between health belief model mean ± SD of subscales and total categories of health belief model pre/post implementation (p < 0.001). Conclusion: It can be concluded that, implementation of the health belief model for overweight secondary school female students led to significant improvements in their knowledge and lifestyle aspects. Recommendation: Apply a preventive program for school students to protect themselves from overweight and obesity.