Very preterm birth is associated with academic difficulties, but the underlying neurocognitive mechanisms of these difficulties remain largely unclear. The present study aimed to assess the role of working memory (WM), attentional processes, and processing speed in academic difficulties of very preterm born adolescents at 13 years. Participants included 55 very preterm and 61 full-term adolescents. Academic performance, visuospatial WM, alerting, orienting, executive attention, sustained attention, and processing speed (simple and choice reaction time [RT]) were compared between groups. Mediation analyses with multiple, parallel mediators were performed to examine whether these functions mediate the relation between very preterm birth and academic performance. Very preterm born adolescents showed poorer reading comprehension, arithmetic, visuospatial WM, alerting, sustained attention, and choice RT than full-term controls. The relationship between very preterm birth and arithmetic was mediated by visuospatial WM, sustained attention, and choice RT. The relationship between very preterm birth and reading comprehension was mediated by visuospatial WM and choice RT. The findings indicate that very preterm birth affects arithmetic and reading comprehension through its negative effect on visuospatial WM, sustained attention, and processing speed. These neurocognitive processes may identify very preterm born children at risk for academic difficulties and could serve as targets for interventions.