BACKGROUND: Bullying has a profound and enduring impact on academic achievement. However, there is a lack of clarity surrounding the specific mechanisms of this relationship. AIMS: This study examined the link between bullying at age 9 and Numeracy/Literacy achievement at age 15 to determine if this relationship is partially or fully explained by psychological difficulties at age 13. SAMPLE: Secondary data analysis was completed on waves 1, 2 and 3 of child cohort (Cohort'98) of the Growing Up in Ireland (GUI) study, respectively, at 9 years (N = 8568), 13 years (N = 7527) and 15 years of age (N = 6216). RESULTS: Longitudinal path mediation model was conducted with bullying at age 9 as the predictor, total (emotional and behavioural) difficulties at age 13 as the mediator and Numeracy/Literacy scores at age 15 as outcomes revealing significant indirect effects of bullying on achievement, via psychological difficulties. CONCLUSIONS: We discuss the impact of bullying on the student's psychological well-being, the relationship between bullying and academic attainment and how this may be tackled to avoid consequences throughout education and later in life. EDUCATIONAL IMPACT AND IMPLICATIONS: This study emphasizes the need for schools to address the emotional and behavioural difficulties occurring as a result of bullying in order to improve the overall educational experience of a child. Existing interventions can be built upon by focusing on the continuous remediation of such psychological difficulties.