Stunting remains a significant public health issue in Indonesia, particularly in Sumedang Regency where prevalence rates remain high. Adolescent girls play a crucial role in future child health, making them ideal targets for preventive health education. Peer education, a method that leverages social interaction among adolescents, is proposed as a promising strategy to enhance knowledge and awareness on stunting prevention. This study aimed to examine the effect of peer education on the knowledge level of adolescent girls in Cipacing Village, Jatinangor District, regarding stunting prevention. This quantitative study employed a quasi-experimental design with a pretest-posttest approach in one group. A total of 25 adolescent girls aged 10–19 were selected using purposive sampling. Data were collected through structured questionnaires administered before and after the peer education intervention and analyzed using a paired t-test. The results showed a statistically significant increase in knowledge after the intervention, with the average score rising from 72.90 to 85.10 (p < 0.000). The percentage of participants with high knowledge increased to 88% post-intervention, indicating the method's effectiveness. The study highlights peer education as a powerful tool for improving health knowledge among adolescent girls. It encourages future programs to adopt similar approaches and suggests further research to evaluate behavioral outcomes and broaden demographic inclusion. These findings contribute valuable insights to local stunting prevention efforts and adolescent health promotion strategies.