Past studies indicate that a number of environmental and psychological factors positively predict the perpetration of cyber-aggression. The main purpose of the present study was to investigate the moderation mediating effect of problematic cyber-activities (FB addiction, phubbing) and culture (Japanese vs. West European) on the association between student burnout and cyber-aggression behaviours among the university student population. In the current studies 171 West European (83% Females, age M = 23.16, SD = 5.46) and 120 Japanese (50% Females, age M = 21.95, SD = 1.62) students. The highest levels of academic dissatisfaction, phubbing, and cyber–aggression in FB-addicted students were found. The phubbing mediated the association between student burnout and cyber-aggression behaviours, but the results for FB addiction in simple mediation analysis were insignificant. Furthermore, FB addiction and culture were significant moderators of phubbing and cyber-aggression behaviours.