The purposes of this study were to develop a short-term online program designed to enhance a growth mindset for university students and to explore its effects on students’ mindset, self-regulated learning (SRL), self-esteem, motivational characteristics related to learning, and academic achievement. After developing the program, 145 undergraduate students from 24 four-year universities were recruited and randomly assigned to an experimental group (n = 71) or a control group (n = 74). The experimental group participated in the short-term online growth-mindset program across two sessions. To explore the effectiveness of the program, independent samples t-tests, repeated-measures ANOVA, ANCOVA, and paired samples t-tests were conducted. The main findings were as follows. First, students in the experimental group showed statistically significant increases in growth mindset and decreases in fixed mindset, and these effects were maintained after three months. Second, regarding the SRL variables, students in the experimental group also showed statistically significant improvements in motivation regulation and its subfactors, and the effects were maintained after three months. However, no significant effect was observed for overall self-regulated learning, cognitive regulation, or behavioral regulation. Third, regarding motivational characteristics, positive effects of the short-term online growth-mindset program were also found on self-esteem, overall academic interest, situational interest, ability attribution about failure, and task difficulty preference. Finally, no significant effect was found on academic achievement. These findings suggest that the short-term online program can effectively enhance students’ growth mindset and also promote positive academic regulation and motivation, implying the practical value of growth mindset interventions and their potential for broader applications.