<![CDATA[Child marriage remains a significant public health issue that adversely affects adolescents' reproductive health, education, and overall well-being. Health education is considered one of the promotive strategies to improve adolescents' knowledge and foster positive attitudes toward preventing child marriage. This study aimed to analyze the effect of health education on adolescents' knowledge and attitudes regarding child marriage prevention among students at SMKS Keluarga Bunda Jambi. This study employed a pre-experimental design using a One-Group Pretest–Posttest approach. The study involved 140 students selected through a total sampling technique. Data were collected using structured knowledge and attitude questionnaires and analyzed using univariate analysis and the Wilcoxon Signed-Rank Test with a significance level of 5%. The results showed that before the educational intervention, 84.29% of respondents had good knowledge, which increased to 100% after the intervention. The Wilcoxon Signed-Rank Test indicated that health education had a significant effect on improving adolescents' knowledge (p = 0.000). Meanwhile, the proportion of respondents with positive attitudes increased from 98.57% to 100%; however, this change was not statistically significant (p = 0.157). The study concludes that health education is effective in improving adolescents' knowledge regarding child marriage prevention but has not demonstrated a significant effect on changing attitudes. Therefore, health education programs should be implemented continuously through collaboration among schools, families, and healthcare professionals to facilitate the transformation of knowledge into positive attitudes and behaviors that support child marriage prevention..]]>
