Creativity, which is a critical skill for college students to meet the complex challenges of the technology-driven world, can be enhanced through online training. Feedback provides learners with assistance in improving their self-regulation, especially for online learning. However, few empirical studies have examined the impact of feedback on online creativity training. Therefore, the present study evaluated the longitudinal effectiveness of an online creativity training and examined the moderating role of feedback. A 12-day intervention (40 minutes per day) online training was delivered to college students via either the feedback training group or the non-feedback training group. College students' creativity was measured in terms of divergent thinking, convergent thinking, and creative self-efficacy. After exposure to the online creativity training, participants showed significant long-lasting improvements in divergent thinking compared to the control group. Notably, the feedback training group retained more training improvement benefits even after the training period and demonstrated significant short-term and long-lasting effects in creative self-efficacy than the non-feedback training group. Besides, regarding convergent thinking, the changes were not significantly different between groups. Overall, the results find evidence for the importance of feedback in such online training, with important implications for the promotion of creativity in higher education.