TikTok is a social media mobile application that is widely used by adolescents, and has the potential to serve as a revolutionary platform for public and mental health discourse, education, and intervention. Our study aimed to describe the content and engagement metrics of the hashtag #teenmentalhealth on TikTok. In this study, we: (a) conducted a directed content analysis of the Top 100 TikTok videos tagged with #teenmentalhealth, and (b) collected data on video engagements (views, likes, saves, and shares) and computed view-based engagement rates. The videos collectively garnered 144,320,591 views; 28,289,655 likes; 219,780 comments; 1,971,492 saves; and 478,696 shares. Most of the generated content were from teens and therapists. Engagement metrics revealed strong user engagement rates across user types. The most prevalent content categories represented across videos were personal experience, coping techniques or treatment, humor, interpersonal relationships, and health campaign. The content categories with the highest engagement rates were relatable media representation, health campaign, social isolation, and humor. Only a single video incorporated evidence-based treatment content. TikTok facilitates communication and information dissemination on teen mental health. Future research should focus on improving the quality and credibility of digital content while maintaining engagement through creativity, self-expression, and relatability. Use of popular social media platforms and community-engaged research to disseminate evidence-based content may help bridge the translational research gap.