This study examines the role of adolescents-parents/teachers/peers relationships as explanatory variables of cyberbullying and problematic Internet-use (PIU) pre-and during COVID-19 pandemic. Questionnaires were delivered to 348 adolescents ages 13 to 18 years (M = 15.05) at two time-points, provided a rare opportunity for assessment the pandemic effect. A significant increase was found in Internet-usage and PIU from pre-pandemic to during the pandemic-lockdown, although no change was found in cyber-perpetrating/victimization, but a decrease in cyber-witnessing. An increase was found in adolescents-teachers/peers relationships, while adolescent-parent relationships remained unchanged and strong. Intensive Internet-use was a positive explanatory variable for stronger teachers/peers relationships. When adolescent-peer relationships were stronger, the cyber-perpetrating/victimization were lower. Also, reinforcements in adolescents-teachers relationships during the lockdown may have influenced the decrease in cyberbullying.