Background: Social media plays a pivotal role in adolescents’ lives. Social media encounters, including online risk behaviors, may influence real-world risk behaviors and mental health. This study explored the magnitude and patterns of social media use, risk behaviors, and mental health among boys and girls and examined associations between these factors.

Methods: A survey was administered to Grade 9 students in New Providence, The Bahamas, in 2023 to assess their social media use, including platforms used, online activities, and experiences of online risk behavior, as well as their risk behavior engagement and mental health. We analyzed data from 1,563 students using generalized linear mixed models.

Results: Two-thirds of the students spent three hours or more on social media daily. Online risk behaviors, such as cyberbullying and sexting (sending, receiving, or forwarding sexually explicit messages), were also prevalent. Approximately 48% had suicidal ideation during their lifetime. Girls reported higher rates of social media usage, active and passive engagement on social media, cyberbullying experiences, and mental health issues, while boys were more likely to engage in sexting and offline risk behaviors. Factors associated with suicidal ideation included being female, experiencing sexting or cyberbullying, using X, and engaging in risk behaviors such as inappropriate touching and weapon carrying.

Conclusions: Future studies should clarify the complex interplay among the content consumed by adolescents, their online activities, and gender-specific effects on mental health. This study highlights the need for programs that can both foster a positive and supportive online environment and provide targeted assistance for victims of online harm.

Supplementary Information: The online version contains supplementary material available at 10.1186/s12889-025-23646-8.