The aim of this study was to examine whether (a) cyberbullying has unique associations with mental health problems, risk-taking, and self-harm behavior in victims and perpetrators when compared to school bullying and (b) if cyberbullying is associated with an additional burden for students already involved in school bullying. Data were collected from 6,561 students across 23 schools in Germany (grades 5-13). The sample was divided into the following four groups: cyber-only involvement (victims = 1.9%, perpetrators = 0.6%), school-only involvement (victims = 17.2%, perpetrators = 11.9%), dual involvement (victims = 5.7%, perpetrators = 2.9%), and noninvolvement (victims = 75.3%, perpetrators = 84.6%). Multilevel mixed-effects regression analysis was conducted to examine group differences in mental health (Strengths and Difficulties Questionnaire, KIDSCREEN-10), risk-taking, and self-harm behavior (e.g., substance use, suicide attempts). Cyber-only bullying had unique associations with mental health problems and risk-taking behavior in victims (lower levels of peer relationship problems: p < 0.001, greater substance use: p < 0.05) and perpetrators (higher levels of peer relationship problems: p < 0.05) when compared to school-only bullying. Dual victims and perpetrators reported significantly more mental health problems (victims: χ2(5) = 221.58, p < 0.001; perpetrators: χ2(5) = 116.40, p < 0.001) and were more likely to report risk-taking and self-harm behavior (victims: χ2(7) = 115.15, p < 0.001; perpetrators: χ2(7) = 38.79, p < 0.001) than students involved in school-only bullying. Cyber-only bullying appears to be related to specific mental health issues beyond those associated with school-only bullying. Cyberbullying and school bullying go along with additive mental health problems, risk-taking, and self-harm behavior in both victims and perpetrators. Thus, bullying prevention and intervention programs should also target cyberbullying.