Purpose: Globally, public health policies are targeting modifiable lifestyle behaviors. We explore the independent association of moderate-to-vigorous physical activity (MVPA) and sedentary behavior on the risk of childhood overweight/obesity. Method: A cross-sectional survey of children aged 8-11 years (N = 826). Objective body mass index was used to classify children as normal weight or overweight/obese. Children wore wrist-worn Geneactiv accelerometers for 7-days and thresholds were applied to categorize MVPA and sedentary time. Screen time (ST) was parent reported. Poisson regression examined the independent association of (1) MVPA (2), objective sedentary time and (3) ST on the risk of overweight/obesity. Results: Overall, 23.7% (95% CI, 20.8-26.6%) of children were overweight/obese. On average, children spent 10.8% of waking time at MVPA and 61.3% sedentary. One-fifth (22.1%, 95% CI, 19.3-25.0%) of children achieved MVPA recommendations (>= 60 min each day) and 17.5% (95% CI, 14.9-20.1%) met ST recommendations (< 2 hr per day). Time spent at MVPA was inversely associated with the risk of overweight/obese independent of total sedentary time. Total time spent sedentary was not associated with overweight/obese independent of MVPA. ST was associated with an increased risk of overweight/obese independent of physical activity. Conclusion: Few schoolchildren met physical activity and screen time recommendations suggesting population based measures are needed.