Background Empowering adolescents in the field of puberty health is one of the important goals of public health programs. The present study was carried out with the aim of determining the effect of peer-led training on puberty-related behavior and its determinants using social cognitive theory. Methods: A total of 245 teenage girls were randomly divided into two groups: the intervention group and the comparison group. The questionnaire measuring puberty-related behavior and its determinants was self-administered and completed before and 2 months after training in the two groups. One session for parents, four sessions for peer educators, and four sessions for participants were conducted for 1 month. Results: In the intervention group, unlike the comparison group, the mean scores of knowledge, outcome expectations, self-efficacy, self-control, social support, and behavior increased significantly after training (p <0.05). Based on regression analysis, outcome expectations and social support were the main determinants of puberty-related behavior (adjusted R² = 0.464). Conclusion: The findings of this study support the effectiveness of the peer-led educational intervention based on social cognitive theory in the improvement of puberty-related behavior and its determinants, which can be used in the design of puberty-related health promotion programs. Further research to assess the longer-term outcomes and to examine other theories of behavior change are suggested.