Adolescence is a critical developmental period marked by increased stress and vulnerability to mental health issues. Meaningful peer relationships are known to protect against these challenges, but the rise of technology and social media use has impacted how adolescents form connections. Research indicates that adolescents' preference for social networks over face-to-face interactions may contribute to loneliness, emotion dysregulation, social media addiction, and the fear of missing out (FoMO). This study aims to examine the mediating role of emotion dysregulation and social media addiction in the relationship between loneliness and FoMO among adolescents. A sample of 342 students (mean age: 12.72, 171 girls, 171 boys) from a public secondary school in Istanbul was surveyed. The UCLA Loneliness Scale-Short Form, the Difficulty in Emotion Regulation Scale-Short Form, the Social Media Addiction Scale for Adolescents, and the Fear of Missing Developments in Social Media Scale were used to collect data. Descriptive statistics and structural equation modeling (SEM) were applied for data analysis. Results showed that both emotion dysregulation and social media addiction fully mediated the relationship between loneliness and FoMO. Bootstrap analyses with 5,000 resamples confirmed the significance of both direct and indirect effects. The findings suggest that greater loneliness is linked to higher emotion dysregulation, increased social media addiction, and heightened FoMO. Interventions aimed at improving social skills, emotion regulation, and reducing social media addiction could help mitigate these effects and support adolescent mental well-being.