Accumulating literature suggests that the risk of perpetrating bullying is greater among those who have been bullied. The association between the transition from victim to bully and revenge aggression suggests the critical role of forgiveness. However, evidence on the mediating role of forgiveness on the victimisation-bullying association is still sparse. The aim of this study was to investigate the mediating effect of person's dispositional forgiveness (DF) on the relationship between cyber-victimisation (CV) and cyber-bullying (CB) and to explore the moderating effect of gender on this relationship. Four hundred eighty-one upper secondary students (n = 481, 47.8% females, mean age = 17.2, SD = 1.5) completed the Florence Cyber-Bullying -- Cyber-Victimisation Scales and the Heartland Forgiveness Scale. Statistical analysis reveals significant direct and indirect effects between CV, DF, and CB latent variables. CV has a negative influence on DF and positive influence on CB behaviour. Furthermore, there was an indirect influence of CV on CB behaviour following the path through DF only in females. The results suggest that DF seems to decrease CB behaviours by buffering the adverse outcomes of being CV, particularly among female victims. The findings underline the relevance of forgiveness within preventative interventions against bullying and cyberbullying.