<p>There has been a significant surge in the use of social media by adolescents. While there are certain advantages to social media, like learning new things and keeping in touch with loved ones, there is growing concern about social media’s detrimental effects on teenage mental health. The purpose of this systematic review is to synthesize the evidence on the relationship between social media content and adolescents’ mental health. The databases ScienceDirect, PsycINFO, and PubMed were used to search the literature. The review included 32 studies. The results suggest that teen use of social media is associated with several poor mental health outcomes, such as depression, loneliness, anxiety, and low self-esteem. Anxiety and depression were the two most prevalent mental health issues. Image-related content on social media was the main factor affecting the mental health of teenagers. Extended screen time and cyberbullying were the most commonly reported pathways through which social media content affects adolescents’ mental health. The findings of this review have many implications for parents, educators, policymakers, and mental health professionals to protect adolescent mental health. This article contributes to informing parents, practitioners, and policymakers to deal with the detrimental effects of social media content on adolescent mental health. This article highlights the importance of engaging various stakeholders in the study of social media and adolescents’ mental health to ensure a healthy digital environment.</p>