Background: This study aims to explore how sufficient social support can act as a possible preventive factor against fighting and bullying in school-aged children in 9 European countries. Methods: Data for this study were collected during the 2013/2014 Health Behaviour in School-aged Children (HBSC) survey. The sample consisted of 9 European countries, involving 43,667 school children in total, aged 11, 13 and 15 years. The analysed data focus on social context (relations with family, peers, and school) as well as risk behaviours such as smoking, drunkenness, fighting and bullying in adolescents. The relationships between social support and violent behaviour variables were estimated using multiple regression models and multivariate analyses. Results: Bullying, across 9 countries, was more prevalent than fighting, except for Armenia, Israel, and Poland. The prevalence among countries differed considerably, with fighting being most expressed in Armenia and bullying—in Latvia and Lithuania. The strongest risk factors for bullying and fighting were male gender (less expressed for bullying), smoking and alcohol consumption. In addition, for bullying the social support was similarly strong factor like above-mentioned factors, while for fighting—less significant, but still independent. All forms of social support were significantly relate with lower violent behaviour of school children, and family support was associated most strongly. Regardless the socioeconomic, historical, and cultural differences among selected countries, the enhancement and reinforcement of the social support from possible many different resources should be taken into consideration in prevention programs against school violence behaviours.