Quantitative analysis of the plantar pressure distribution during dynamic tasks can facilitate diagnosis of foot and ankle dysfunctions and prevent potential injuries by providing detailed information about weight bearing and weight shifting patterns. Traditional laboratory measurements are currently limited by high operating costs and lack of portability. The use of instrumented insoles capable of capturing kinematic and kinetic gait parameters as subjects perform out-of-the-lab dynamic activities is a promising approach to overcome these limitations. This letter introduces SportSole, a fully portable system that can measure spatiotemporal gait parameters and center of pressure (CoP) trajectories. Wearing the SportSole, nine able-bodied subjects completed a walking session followed by a running session, each consisting of 10 full laps along a 16-meter straight-line path. Accuracy and precision of CoP trajectories and kinematic parameters were assessed using an electronic walkway as the reference system. After calibration, mean deviations in the CoP were 0.61 ± 0.05 cm (RMSE ± SD) for walking and 0.72 ± 0.08 cm for running. Deviations in stride length, stride time, and velocity were 1.66 ± 0.18 cm, 0.006 ± 0.003 s, and 1.65 ± 0.10 cm/s for walking, 1.91 ± 0.19 cm, 0.01 ± 0.03 s, and 2.67 ± 0.38 cm/s for running. These promising results indicate that the proposed system has the potential to be used for out-of-the-lab gait analysis of walking and running.