Objectives: This study aimed to estimate the prevalence of social media usage and Internet addiction among Oman Medical Specialty Board (OMSB) residents and to determine associations between Internet addiction and sociodemographic characteristics and symptoms of depression. Methods: This cross-sectional study took place between January and March 2017. All 499 residents enrolled in OMSB training programmes during the 2016–2017 academic year were targeted. A self-administered questionnaire was distributed to collect information concerning sociodemographic characteristics. In addition, the Patient Health Questionnaire-9 and Internet Addiction Test were used to screen for depression and Internet addiction, respectively. Results: A total of 399 residents participated in the study (response rate: 80%). Overall, 115 residents (28.8%) had varying degrees of depression and 149 (37.3%) were addicted to the Internet; moreover, among those addicted, 54 (36.2%) had depression. While no significant associations were observed between Internet addiction and sociodemographic characteristics, the association between Internet addiction and depression was statistically significant (P = 0.004). Conclusion: Internet addiction was clearly detected among OMSB residents, with a significant association observed between Internet addiction and depression. Although a causal link between these two variables cannot be established as depression is multifactorial in origin, the disadvantages and harmful effects of excessive Internet and social media usage need to be addressed. Further research on the consequences of Internet addiction and its effect on quality of life and academic achievement is recommended. Keywords: Internet; Social Media; Social Networking; Addictive Behaviors; Depression; Medical Students; Oman.