Background Despite the adverse externalising risks associated with bullying victimisation, no study has investigated the underlying mechanisms of adolescent victims' engagement with alcohol. This current study investigated the development of risky coping drinking motives as a mediator in the relationship between adolescent school victimisation and alcohol-related problem behaviour using a longitudinal design over 12 months. Method We recruited 324 participants, aged 13 to 15 from schools across London, England. Participants were surveyed during class time at 2 time points: baseline and 12 months. At both time points participants answered questions related to bullying victimisation, alcohol-related problem behaviour, drinking motives and the quantity by frequency of alcohol consumption. Results The relationships between victimisation, drinking and drinking motives were investigated using Pearson correlations. Path analysis showed that victimisation leads both directly and indirectly, through coping motives to alcohol-related problems, rather than to the quantity and frequency of alcohol use. Significance of mediation was tested using 5000 bias corrected and accelerated bootstrapped intervals. Baseline victimisation was significantly correlated with baseline alcohol-related problem behaviour and predictive of future problems at 12 months. Drinking to cope at 12 months partially mediated the relationship between baseline victimisation and alcohol-related problems at 12 months. Conclusions Results show that victims of bullying are drinking alcohol in a risky style, partly due to the development of self medicating drinking behaviour. Victims of bullying could therefore benefit from coping skills interventions targeting negative affect regulation in order to reduce the risk for future alcohol misuse.