Childhood wellbeing is essential for positive outcomes in adulthood, as is academic attainment. Schools play a pivotal role in laying the foundations for children to live well. However, research investigating the relationship between wellbeing and attainment has relied on conceptualisations of wellbeing that are too broad (i.e. overall and domain-general wellbeing) or samples spanning large age ranges (thereby overlooking developmental differences). Additionally, the role of mindset, a potentially co-occurring psychological state of both wellbeing and attainment, has been neglected. This study therefore investigated the wellbeing-attainment relationship in 942 children aged 9-11 (447 male, M[subscript age] = 10.5; 495 female, M[subscript age] = 10.6) across 17 schools in England (UK). Structural equation models distinguished between overall wellbeing, life satisfaction, and eudaimonia, examining associations of each with children's attainment on standardised tests, accounting for mindsets, achievement goals, and sociodemographic factors. Results indicated lower life satisfaction was significantly associated with higher attainment on average, and in English and Mathematics, while eudaimonia was not significantly related to attainment. Overall wellbeing was negatively associated with Mathematics attainment only. A growth mindset was "positively" associated, while a fixed mindset was "negatively" associated, with wellbeing. In turn, a growth mindset was significantly "positively" associated, while a fixed mindset was "negatively" associated, with attainment. Implications for policy and practice are discussed.