Introduction: Adolescent reproductive health remains a significant public health concern, particularly in developing countries where access to accurate reproductive health information is often limited. Social media has emerged as a widely used communication platform among adolescents and may serve as an alternative medium for reproductive health promotion. This study aimed to analyze the effectiveness of social media as a health promotion tool for reproductive health among adolescents. Research Methodology: A quantitative cross-sectional analytical study was conducted among 250 adolescents from selected senior high schools in Makassar, South Sulawesi, Indonesia. Respondents were selected using stratified random sampling. Data were collected through a structured self-administered questionnaire assessing information accessibility, perceived credibility, user engagement, and frequency of exposure to reproductive health content on social media. Data analysis was performed using descriptive statistics, Chi-square tests, Pearson correlation tests, and multiple logistic regression, with a significance level of α = 0.05, in SPSS version 26. Results: Perceived credibility was the strongest predictor of social media effectiveness in reproductive health promotion (AOR = 3.06; 95% CI: 1.67–5.59; p < 0.001). Frequent exposure to reproductive health content was significantly associated with higher perceived effectiveness (AOR = 2.39; 95% CI: 1.28–4.46; p = 0.004). High user engagement (AOR = 2.10; 95% CI: 1.16–3.79; p = 0.011) and information accessibility (AOR = 2.54; 95% CI: 1.39–4.65; p = 0.002) were also significantly associated with positive educational outcomes. Conclusion: Social media is an effective platform for reproductive health promotion among adolescents when information is accessible, credible, and interactive. The findings highlight the importance of evidence-based digital health communication and support, integrating adolescent-centered social media strategies into reproductive health promotion programs