Objective: We examined relationships among academic achievement, cardio-respiratory fitness (CRF), physical activity (PA), and frontal plane dynamic postural stability (DPS) in pre-adolescent children. Methods: A cross-sectional study was performed with 853 year-5 and year-6 students examining relationships among Australian national education test results, and CRF, PA and DPS data. Correlation and multiple regression analyses were employed together with extreme quartile grouping of physical performance scores, comparing the effect on their academic scores. Results: Only semi-tandem DPS was associated with all academic variables. The best performing quartile group in semi-tandem DPS, CRF and PA significantly outperformed the worst for most academic tasks, with small to moderate effect sizes. Conclusion: Frontal plane semi-tandem DPS was more closely associated with all academic variables than PA and CRF. Given the observed relationships to academic success, promoting semi-tandem DPS in conjunction with increased PA and CRF levels for primary school children is supported.