<p>This systematic review and meta-analysis examined the relationship between psychological capital and mental health among Chinese university students. Following PRISMA guidelines, we searched seven databases (2010–2024) and included 52 studies involving 59,869 participants. Using random-effects models, results revealed a significant positive correlation between psychological capital and mental health (<i>r</i> = 0.47, 95% CI [0.44, 0.50]), indicating a medium-to-large effect. Among the four dimensions, optimism showed the strongest association (<i>r</i> = 0.51), followed by hope (<i>r</i> = 0.48), resilience (<i>r</i> = 0.45), and self-efficacy (<i>r</i> = 0.42). Psychological capital demonstrated stronger effects on positive mental health indicators (<i>r</i> = 0.48–0.52) than negative indicators (<i>r</i> = -0.40 to -0.45). Gender composition and publication period significantly moderated effect sizes. Sensitivity analyses confirmed result robustness, with no evidence of publication bias. These findings validate psychological capital as an important protective factor for Chinese university students’ mental health and support shifting from problem-focused interventions to positive resource-building approaches in university mental health education.</p>