Background: Problematic smartphone use has increasingly become the focus of attention in recent years. Although it has been noted that parental psychological control is significantly correlated with teenagers’ social anxiety and problematic smartphone use, little is known about how these factors may interact with college students. Therefore, the purpose of this study is to investigate whether social anxiety mediates the association between parental psychological control and problematic smartphone use. Methods: a total of 534 Chinese college students aged 17–25 years (male 59.0%, female 41.0%) participated in the study (M = 20.40, SD = 1.72). The Parental Psychological Control questionnaire, the Social Phobia Inventory, and the Mobile Phone Addiction Tendency Scale were used to evaluate parental psychological control, social anxiety, and problematic smartphone use, respectively. Data were analyzed using the Pearson correlation analysis, regression analysis, and mediation analysis. Results: the results showed that (1) social anxiety was positively correlated with problematic smartphone use among college students, (2) parental psychological control has a significant correlation with college students’ social anxiety, (3) college students’ social anxiety was positively related with problematic smartphone use, and (4) social anxiety plays a mediation role in the association between parental psychological control and problematic smartphone use. Conclusions: in conclusion, social anxiety plays a mediating role in the relationship between parental psychological control and problematic smartphone use, and reducing parental psychological control is an effective intervention means to directly or indirectly reduce college students’ problematic smartphone use. In addition, attention should be paid to parenting styles, and measures should be taken to increase social interaction among college students so as to reduce their problematic smartphone use.