Balancing out-of-class time for college students is not only crucial for reducing academic and emotional burdens but also plays a significant role in students' development. Using a work-life balance framework, this study proposes a theoretical framework of the balance between academic and non-academic time involvement and defines different balance statuses among undergraduate students. To examine the impacts of balance and imbalance, data were collected from 817 undergraduate students at a Chinese university through an online survey. Polynomial regression and response surface analysis, a method that models the impacts of the balance and imbalance between two variables, were used to assess how different balance statuses affect educational gains and depression. The findings reveal that most positive balanced students who allocate a significant amount of time to both academic and non-academic activities report more educational gains and less depression compared to those negative balanced individuals who invest small amounts of time in both domains. Compared with imbalanced students, balanced students achieve more educational gains and are less prone to depression. Regarding imbalanced students, academically imbalanced individuals tend to achieve more educational gains than those non-academically imbalanced. These results provide direct evidence supporting the importance of maintaining a positive balance between academic and non-academic life for undergraduate students, which calls for educators and institutions to promote and support a balanced student experience.