Although the growth mindset is essential to students' math achievement, its mechanism of influence remains uncertain, particularly for college students. Accordingly, this study explored the relationship between college students' growth mindset and their math achievement, as mediated by their self‐efficacy and reasoning ability. The study data were gathered by surveying 576 undergraduates taking various undergraduate programs at a Chinese university. Our results showed that (1) students' growth mindset did not directly predict their math achievement; (2) self‐efficacy mediated the relationship between students' growth mindset and their math achievement; and (3) the growth mindset affected students' math achievement through the chain‐mediation of self‐efficacy and reasoning ability. Overall, the finding that the growth mindset indirectly benefits Chinese college students' math achievement provides invaluable guidance to higher education professionals aiming to develop more effective math programs. Moreover, the mediating effects of self‐efficacy and reasoning ability were also theoretically important to better understand the potential influence mechanism of the growth mindset on college students' math achievement.