Objective: To investigate the impact of cognitive fusion on mobile Phone dependence among college students and the underlying psychological mechanisms. Methods: A survey using the mobile Phone Addiction Scale, the fear of missing out Scale, and the Chinese version of the Cognitive Fusion Questionnaire was conducted among 576 college students. Results: Correlation analyses showed significant positive correlations between cognitive fusion and mobile Phone dependence, as well as fear of missing out (r=0.47, 0.56; p<0.001); there was also a significant positive correlation between fear of missing out and mobile Phone dependence (r=0.55; p<0.001). Mediation effect analysis indicated that cognitive fusion not only directly predicted mobile Phone dependence among college students (β=0.46, p<0.001) but also indirectly predicted it through the mediating role of fear of missing out (β=0.34, p<0.001), with the mediation effect accounting for 36%. Conclusion: mobile Phone dependence is relatively common among college students. Cognitive fusion can directly influence mobile Phone dependence and can also indirectly affect it through the mediating effect of fear of missing out.