Social media addiction has become a serious public health concern due to its adverse psychological effects. Therefore, the purpose of this study was to assess the prevalence and determinants of social media addiction among medical students in Saudi Arabia. A cross-sectional study was designed. Participants (n= 326) from King Khalid University in Saudi Arabia completed the sociodemographic information, patient health questionnaire-9 scale, and the generalized anxiety disorder-7 tool to measure explanatory variables. The Bergen social media addiction scale (BSMAS) was used to measure social media addiction. A multiple linear regression model was fitted to investigate the predictors of social media addiction. The prevalence of social media addiction among study participants was 55.2% (mean BSMAS score: 16.6). According to the adjusted linear regression, male students had higher social media addiction scores than their female counterparts (β = 4.52,p< 0.001). Students’ academic performance was negatively associated with social media addiction scores. Moreover, students with symptoms of depression (β = 1.85,p= 0.005) or anxiety (β = 2.79,p= 0.003) had a higher BSMAS score compared to their counterparts. Further longitudinal studies are warranted to identify the causal factors of social media addiction, which would assist intervention initiatives by policymakers.