Background <p>Bullying, problematic internet gaming, and problematic social media use are concerning phenomena, especially among youth. However, studies including all three of them are scarce. Therefore, this study investigated the associations between bullying victimization and the two internet-related outcomes. Furthermore, differences between problematic internet gaming and problematic social media use regarding the individual and moderating effects of gender, age, educational background and mental health problems were examined.</p> Methods <p>Adolescents (<i>N</i> = 6,735; 48.85% females) answered a school-based survey on bullying, problematic internet gaming, problematic social media use and mental health problems. The age ranged from grade 5 with <i>M</i> = 10.77 years (<i>SD</i> = 0.68) to grade 9 with <i>M</i> = 14.75 years (<i>SD</i> = 0.87) and overall <i>M</i> = 12.73 years (<i>SD</i> = 1.60). A-level school students represented higher educational background (39.52%) while B-level school students represented lower educational background (60.48%). Multilevel modelling was used to examine the associations of bullying victimization with problematic internet gaming and problematic social media use as well as the influences of gender, school grade as a correlate of age, school type and mental health problems.</p> Results <p>Victims of bullying showed higher odds for problematic internet gaming and problematic social media use. Overall, boys showed higher levels of problematic internet gaming, whereas girls showed higher levels of problematic social media use. Younger adolescents reported higher odds for problematic internet gaming, while no age effect was found for problematic social media use. Students with lower educational background and those with more mental health problems reported more problematic social media use than problematic internet gaming. Mental health problems moderated the association of bullying victimization with problematic internet gaming and problematic social media use, with stronger relations for students with less mental health problems. Furthermore, gender was a significant moderator for problematic social media use but not for problematic internet gaming, with a stronger association for boys.</p> Conclusions <p>Bullying victimization is strongly related to different types of problematic internet use. As differences in the impact on problematic internet gaming and problematic social media use can be identified, prevention should also consider gender, age, educational background and mental health problems.</p> <p><i>Trial registration</i> DRKS00028183.</p>