Many researchers have examined the potential detrimental role of problematic social media use (often referred as 'social media addiction') on mental health. The present study investigated how social media addiction is associated with three components of mental health: depression, anxiety, and stress. In addition, structural equation modeling was used to test the mediating roles of internet addiction and phubbing among a sample of young adults ( = 603). Results showed that social media addiction was associated with poorer mental health via internet addiction and phubbing. More specifically, associations between social media addiction and stress, and social media addiction and anxiety were explained by both internet addiction and phubbing. The association between social media addiction and depression was explained by internet addiction only. These results remained consistent after controlling for gender, age, frequency of internet use, frequency of social media use, and frequency of smartphone use. These findings extend the extant literature by providing evidence for the dual roles of internet addiction and phubbing in explaining the relationship between social media addiction and poor mental health. Social media addiction did not directly influence poorer mental health but did via internet addiction and phubbing. Therefore, greater awareness of the inter-relationships between technology-based behaviors and their impact on mental health is needed among a wide range of stakeholders, and these inter-relationships need considering in the prevention and treatment of technology-based disorders.