Background: Bangladesh has one of South Asia’s highest rates of child marriage, making female adolescents vulnerable to reproductive health risks. Shornokishoree (SK) Network has been implementing a mobilization program in Bangladesh using a variety of community engagement approaches. The main objective is to raise awareness among adolescents in secondary schools, bringing together as many stakeholders as possible. This paper aims to examine the effectiveness of the Network’s interventions and to determine changes in adolescents’ knowledge, attitudes and practices to prevent child marriage.   
Methods: 630 participants were recruited from 35 secondary schools across eight divisions of Bangladesh. This study adopted a quasi-experimental design and consisted of a sample for intervention (308) and control group (322). The intervention group consisted of the participants who attended awareness sessions regarding early marriage and reproductive health issues. The study was conducted using stratified random sampling technique. Data were collected through a structured questionnaire and analyzed using SPSS version 23. Chi-square and z-tests were performed to assess the program’s effectiveness including associated factors.
Results: The study shows that knowledge about child marriage remained significantly lower (p < 0.01) for the control group compared to the intervention group. Nearly one-third (27.9%) of the experimental group rejected the assumption that women’s marriageability begins with puberty. 38.4% of the participants in the  control group were unaware of the consequences of adolescent pregnancy compared to 8.1% of the intervention group (p < 0.01). Additionally, 29.9% of the control group had a very limited understanding of the child mortality and maternal death issues compared to 6.8% of the intervention group (p < 0.01).
Conclusion: The study concluded that the awareness program has been very useful in improving knowledge about child marriage among adolescents, creating an impact on child marriage prevention.