Background: Depression and its related variables are especially interesting and important to study in the context of the virtual world. Objectives: The purpose of the present study was to investigate the relationship between screen time, the amount of social network usage, and physical activity with depression in students. Methods: The research method was a descriptive correlation study. One hundred sixty undergraduate students from Qazvin Universities were selected as a sample in the spring of 2022 using multi-stage cluster sampling. After dropping some subjects, the sample size was reduced to 146. The participants completed questionnaires about screen time, social network usage, physical activity, and depression. The obtained data were analyzed using Pearson's correlation coefficient and simultaneous regression. Results: The results showed a significant relationship between screen time and depression (r = 0.35, P < 0.01). There was also a significant relationship between the use of social networks and depression (r = 0.17, P < 0.05), but no relationship was observed between physical activity and depression (r = 0.08, P > 0.05). Additionally, it was found that the predictor variables could explain 13% of the variance in the depression variable. Conclusions: The contribution of the screen time variable in explaining depression symptoms was higher than that of the other variables.