BackgroundSuicide is a fatal public health issue for adolescents, and it is of great significance to explore the precursors of suicidal behaviors, especially suicidal ideation. However, the relationship between social anxiety and suicidal ideation and its mechanism are still unclear. The study aims to examine the association between social anxiety and suicidal ideation and the mediating effect through Internet addiction.MethodsA total of 2,278 middle-school students aged 12 to 16 years were recruited through a multistage cluster sampling method in this cross-sectional study. Logistical regression analysis and structural equation modeling (SEM) were conducted to examine the direct and indirect effects of social anxiety.ResultsDuring the past year, 262 (11.50%) participants reported suicidal ideation. Females had a higher prevalence of suicidal ideation than males (12.9% vs. 10.0%, p = 0.034), and urban adolescents reported a higher prevalence than their rural counterparts (13.4% vs. 9.6%, p = 0.006). In the total sample, social anxiety and Internet addiction were independently associated with suicidal ideation (p