The Polar H10 is a low-cost wearable with a heart rate monitor and tri-axial accelerometer with potential for many applications. While the device’s heart rate monitor has been widely studied, there is no research validating the accelerometer specifically. The purpose of this study was to conduct a validation of the Polar H10 accelerometer to establish static and dynamic validity during a sports-based task. Static validity was determined by computing the relative error when using a level guide to hold each axis of the Polar H10 against gravity. Fifteen healthy adults (8F/7F) participated in sports-based tasks while wearing the Polar H10 (Polar Electro, Poland) and a comparison device, the MetaMotionR inertial measurement unit (MbientLab Inc., USA). Dynamic validity was characterized using Pearson’s correlation coefficient and root mean square error (RMSE). Additionally, common features in human activity recognition (mean magnitude, root mean square, power, and signal magnitude area) were computed in 2s windows and compared via RMSE and Wilcoxon rank sum tests. When held against gravity, the Polar H10 had relative errors ranging from 2.620% to 4.288%, suggesting high static validity. During sports-based tasks, the accelerometers had correlations between 0.888 and 0.954, indicating sufficient concurrent validity for all axes, as well as acceleration magnitude. The differences in acceleration features were minimal (RMSE for mean, root mean square, power, and signal magnitude were 0.003G, 0.004G, 0.112, and 0.017G, respectively), but all reached significance (P<.001). These results provide evidence for the use of the Polar H10 accelerometer to measure movement during sport-like activities.