Background: To examine the associations between children's organized physical activity (OPA), nonorganized physical activity (NOPA), and health-related outcomes (fundamental movement skill [FMS] fitness). Methods: Cross-sectional survey of children aged 10-16?years (N?=?4273). Organized physical activity and NOPA were assessed by self-report, FMS by process-orientated criteria, and fitness by 20-m shuttle run test. Results: Boys spent 97.5?minutes and girls 86.6?minutes in daily physical activity with the majority spent in OPA (boys, 56.3%; girls 60.5%). Organized physical activity increased with grade, whereas NOPA decreased. Organized physical activity and NOPA were associated with fitness, and OPA was consistently associated with FMS competency. Boys' fitness was associated with OPA and NOPA (adjusted odds ratio [AOR] 1.42, 95% confidence interval [CI]: 1.04, 1.94; AOR 1.26, 95% CI: 1.03, 1.54, respectively), FMS competency (side gallop leap, kick) with OPA and catch, and over-arm throw with both OPA and NOPA. Girls' fitness (AOR 2.62, 95% CI: 1.88, 3.66) and FMS competency were consistently associated with OPA. Conclusions: Both OPA and NOPA are important contributors to children's physical activity; however, for girls, OPA was more strongly associated with fitness and FMS competency. Our findings support the importance of providing children with opportunities to engage in daily OPA. School physical education programs are an ideal delivery vehicle for OPA and need to be central to education policy.