Abstract: Social media is a constantly growing part of adolescents’ lives and is becoming more widely used as technological advancement has grown over the years. It has been shown to be driven by positive and negative gratifying experiences. However, a clear understanding regarding the effects social media has on adolescents’ mental health, as well as the reasons social media is so widely used is still uncertain. This study explored the social media usage amongst Malaysian adolescents in terms of the factors affecting social media usage and the effects it has on their mental health. A qualitative phenomenological approach was used to gather data, by interviewing 10 Malaysian adolescents from Kuala Lumpur and Selangor. Data analysis was conducted by analysing common themes and coding the data accordingly. The results showed that Malaysian adolescents use social media for both positive and negative purposes. Positive purposes included to seek information, to communicate with others, as well as decrease negative mood and boredom. Negative purposes included to seek online validation, due to the fear of missing out, addiction, and the anticipation of positive effects in the future. This is of concern as these purposes caused some to experience more negative than positive effects on their mental health, such as an increase in negative mood and a decrease in self-esteem.