In contemporary society, social media use has become a widespread daily activity, especially among adolescents, who are often engaged in visual content sharing. Taking and posting selfies on social media is one of the most popular activities associated with teens' social media use, representing a useful tool to increase their self-presentation via others' approval. However, higher exposure to visual content on social media might lead to more social comparisons and appearance concerns reinforcement. Therefore, body image-based digital activities might allow dissatisfied individuals with their appearance to create and manage their best online self-presentation, leading to potentially problematic social media use. The present study evaluated the unexplored predictive role of selfie-expectancies and social appearance anxiety on problematic social media use (referred to by some scholars as ‘social media addiction’), as well as examining the possible gender differences between boys and girls. A total of 578 adolescents (mean age 16.1 years) participated in the study. Results showed that boys' anxiety concerning self-appearance and the expectancy that selfies could improve their self-confidence were both predictors of their problematic social media use. On the contrary, despite a higher level of social appearance anxiety among girls, it did not influence their social media use. The study demonstrated novel findings concerning new gender-related associations in relation to problematic social media use, social appearance anxiety, and teens' expectancies underlying selfie behavior. •Selfie-expectancies differently predict social media misuse in both genders.•Appearance concerns predict only boys' problematic social media use.•Selfie behavior did not appear to be a mainly female phenomenon.•Teens' bodily appearance represent a pivotal issue in problematic social media use.