Background: This study examines the effects of physical education on the social capital of university students, focusing on improving family, neighborhood, and academic relationships through group exercise. Methods: In Zagreb, Croatia, 976 participants aged 19–20 years participated in a randomized controlled trial. The intervention group (n = 472) engaged in teamwork exercises, and the control group (n = 504) completed individual exercises. The social capital measured in 6 areas was analyzed using linear regression and variance modeling. Results: Significant improvements in trust and collaboration within the university environment were found in the intervention group. Adjusted analyses showed positive correlations between the physical education intervention and increased trust between teachers and students (β = 0.118, P = .01), among students (β = 0.246, P = .01), and in total social capital (β = 0.617, P = .01). Residence in the parental home was associated with higher social capital. Notably, male and older students reported lower levels of trust and cooperation. Conclusions: Physical activity significantly improves the social capital of university students, suggesting the inclusion of group-based physical activities in higher education curricula to promote social inclusion and well-being. This underscores the importance of such interventions for educational policy and program development.