Adolescents nowadays experience significant mental and behavioral changes, largely influenced by the pervasive use of social media, the rise in peer influence, and the fear of missing out (FoMO). However, many crucial questions regarding the relationships between social media, peer influence, and FoMO remain unanswered. Therefore, this study was conducted to explore the interconnections among social media processes, FoMO, and peer influence among secondary and high school students, with a specific focus on posts sharing academic achievements or experiences among peers. The research employed a quantitative approach, using a 5-point Likert scale questionnaire to collect data via an online survey. A total of 419 valid samples were collected and analyzed using factor analyses and structural equation modeling (SEM). The findings revealed that certain social media experience processes, namely online peer norms and novel peer experiences, significantly influenced both peer influence and FoMO. While online peer norms affected both phenomena, novel peer experiences only had an impact on peer influence. Moreover, FoMO played a mediating role in the relationship between social media experience and peer influence. Based on these findings, the study proposes solutions to optimize the impact of social media on adolescents. Gaining insights into the dynamics of social media processes, FoMO, and peer influence can enhance support for adolescents’ mental well-being and address challenges in the digital age.