<p>This study explores the impact of online social interaction on college students’ socio-emotional competence in the digital age, as well as its potential mediation mechanisms. Bonding social capital, represented by parent-child and peer relationships, was selected as the mediating variable. Using data from 693 college students in the 2022 China Family Panel Studies (CFPS), this paper analyzes the relationship between online social interaction and socio-emotional competence in college students. The findings indicate that online social interaction does not have a significant direct impact on socio-emotional competence, but it indirectly enhances college students’ socio-emotional competence by strengthening bonding social capital. Furthermore, gender and urban-rural differences exhibit some heterogeneity in this relationship, with a more significant mediating effect of bonding social capital among male and rural college student groups. The results provide new insights into how digital technology, through social relationships, affects college students’ socio-emotional competence and offer important implications for educational practices and family education.</p>