<p>To investigate the relationship between cyberbullying victimization and the nonsuicidal self-injury behavior of students in three vocational colleges in China and explore the mediating role of intrusive rumination and the moderating role of gender. A cross-sectional survey was conducted with 4,465 students from three vocational colleges in China. Valid questionnaires (<i>n</i> = 4,343; response rate: 97.27%) were analyzed via the Cyberbullying Victimization Scale, the Adolescent Self-Harm Questionnaire, the Event-Related Rumination Questionnaire (Chinese version), and demographic measures. Data analysis included correlation tests, mediation analysis, and moderated mediation analysis. (1) Cyberbullying victimization was positively linked to nonsuicidal self-injury behavior (<i>β</i> = 0.24, <i>p</i> &lt; 0.001, <i>95% CI</i> [0.21,0.27]). (2) Intrusive rumination partially mediated the relationship between cyberbullying victimization and nonsuicidal self-injury (indirect effect: 0.07, <i>95% CI</i> [0.05, 0.09]). (3) Gender plays a moderating role in the three pathways. CV → NSSI: Stronger in women (<i>β</i> = 0.32) vs. men (<i>β</i> = 0.26), CV → IR: Stronger in women (<i>β</i> = 0.33) vs. men (<i>β</i> = 0.29), IR → NSSI: Stronger in women (<i>β</i> = 0.30) vs. men (<i>β</i> = 0.24). Cyberbullying victimization directly and indirectly (via intrusive rumination) is associated with increased NSSI risk among vocational college students. Gender significantly amplifies this mediation pathway, with consistently stronger effects observed in women across all associations.</p>