This study examined whether social self-efficacy and experiential avoidance mediate the relationship between intolerance of uncertainty (IU) and social anxiety among college students. A cross-sectional survey was conducted with 394 college students (aged 18-29) from South Korea. Data were analyzed using SPSS 25.0 and PROCESS macro 4.3. Measures included the Intolerance of Uncertainty Scale (IUS-12), the Social Self-Efficacy Scale for College Students, the Korean version of the Multidimensional Experiential Avoidance Questionnaire (K-MEAQ-24), and the Social Anxiety Scale for College Students. Results indicated significant correlations among all primary variables. Both social self-efficacy and experiential avoidance independently mediated the association between IU and social anxiety. Additionally, a significant serial mediation was observed: higher IU was associated with lower social self-efficacy, which in turn predicted greater experiential avoidance and subsequently higher social anxiety. These findings clarify a psychological pathway linking intolerance of uncertainty to social anxiety in college students and suggest that interventions aimed at enhancing social self-efficacy and reducing experiential avoidance may mitigate social anxiety in this population.