Objectives: This study examined the effects of bullying victimization on cyberbullying perpetration and investigated whether hopelessness and time spent online sequentially mediate the relationship between bullying victimization and cyberbullying perpetration among upper elementary students.Methods: The participants were 596 upper elementary school students {5th and 6th graders; 291 boys (48.8%)} from Seoul and Gyeonggi-do. The data were collected through a self-report questionnaire and analyzed using SPSS 26.0 and PROCESS macro version 4.3 (Model 6) by Hayes (2017).Results: First, bullying victimization positively influenced cyberbullying perpetration. Second, the sequential mediating effects of hopelessness and time spent online were significant. Lastly, time spent online mediated the effect of bullying victimization on cyberbullying perpetration, whereas hopelessness did not mediate this effect.Conclusion: These findings indicate a link between bullying victimization and cyberbullying perpetration. Therefore, it is recommended that cyberbullying prevention programs include strategies to reduce bullying victimization. Furthermore, high levels of hopelessness resulting from bullying victimization may lead to excessive internet use, increasing the likelihood of cyberbullying perpetration. Thus, victims need to be informed of about the importance of reporting bullying incidents to adults such as teachers, counselors, or parents. Additionally, if victims already exhibit high levels of hopelessness, it is necessary to encourage them to participate in evidence-based programs. Finally, the significant mediating effect of time spent online suggests that monitoring and intervening in victims’ online activities are crucial for reducing the likelihood of cyberbullying perpetration. These efforts may help prevent victims from spending excessive time online to relieve their hopelessness and from perpetrating cyberbullying.