Background Adolescence is a critical period for individual growth and development. Insufficient sleep adversely affects adolescents' physical development, blood pressure, vision, and cognitive function. This study examined the effect of short-form video addiction on adolescents' sleep quality, as well as the mediating role of social anxiety, to identify methods for improving adolescents' sleep quality in the Internet era. Methods A questionnaire survey was conducted in this cross-sectional study on 1629 adolescents recruited from three high schools. Their short-form video addiction, social anxiety, and sleep quality were evaluated using corresponding scales. Pearson correlation analysis was carried out to analyze the relationships among short-form video addiction, sleep quality, and social anxiety. Mediating effect analysis was constructed using AMOS 20.0 statistical software. Results Participants' sleep quality score is 6.12 +/- 3.29 points. The detection rate of sleep quality among them is 31.06%. Short-form video addiction, sleep quality, and social anxiety are significantly correlated (r = 0.439, 0.404, 0.457, P < 0.001). The direct effect of short-form video addiction on sleep quality is 0.248, accounting for 62.4% of the total effect. The indirect effect exerted through social anxiety is 0.149, accounting for 37.6%. Conclusions Sleep disorders are very common among Chinese adolescents. Short-form video addiction is positively correlated with adolescents' sleep quality and social anxiety. Social anxiety partially mediates the relationship between short-form video addiction and sleep quality. The adverse effects of short-form video addiction and social anxiety on the sleep quality of this group must be minimized. Schools are recommended to implement measures to promote sleep quality among adolescents.