Smart GenRe (Sistem Manajemen Aksi Remaja Terampil Generasi Berencana) is a creativity development system for teenagers implemented by the GenRe Forum of Cilegon City. Early marriage in Cilegon City is the second highest in all cities in Banten Province, and adolescents’ understanding of the maturity of marriage age is still limited. This study aims to determine the effectiveness of the Smart GenRe application in enhancing the knowledge of its users regarding early marriage in Cilegon City. This quantitative study was conducted from March to July 2024, involving 285 application users selected using the quota sampling technique. Data were collected through questionnaires and interviews. The results showed a significant effect of the Smart GenRe application on user knowledge about early marriage in Cilegon City, with a correlation coefficient of 0.986 and a significance value of 0.000 (p<0.05). To further enhance adolescents’ understanding and prevention of early marriage, it is recommended that D3PAP2K BKKBN Cilegon City routinely conduct counseling and educational outreach about the appropriate age of marriage. These efforts will help adolescents complete their education and achieve emotional and financial readiness before entering married life.