Growth mindset has attracted considerable scholarly attention as a predictor of academic outcomes, yet the psychological pathways linking it to students' perceived learning gain remain insufficiently understood, particularly in Chinese higher education settings. This study examines the association between growth mindset and learning gain among Chinese college students and investigates whether academic self-efficacy serves as a mediating mechanism. A cross-sectional survey was administered to 478 undergraduates from three universities in Hubei Province, central China, using validated instruments for growth mindset, academic self-efficacy, and learning gain. Structural equation modeling with bias-corrected Bootstrap resampling was used to test the hypothesized mediation model. Results indicated that growth mindset was positively associated with learning gain, and that academic self-efficacy partially mediated this association. These findings integrate Dweck's implicit theory of intelligence with Bandura's self-efficacy framework within a single analytical model, offering evidence that growth mindset relates to learning gain both directly and indirectly through its association with academic self-efficacy. Practical implications for designing mindset and self-efficacy interventions in Chinese universities are discussed.