Purpose: The purpose of this study was to compare gait ground reaction forces (GRF) between children, adults, and older adults. Methods: Twenty-five children (6.13 ± 1.86 years), 30 adults (34.37 ± 5.67 years), and 33 older adults (70.45 ± 6.92 years) walked on force platforms. Velocity, GRF, and impulses were calculated. Results: Gait velocity was higher in children compared to older adults (p = 0.031). Gait velocity had an inverse effect in GRF parameters across all groups. The vertical peak of force appeared at 22% of the gait cycle in children, at 27.3% in adults, and at 25.7% in older adults. The anterior–posterior force peak appeared at 14.8% of the gait cycle in children, at 17.1% in adults, and at 16.5% in older adults. Ground reaction forces were higher in children (p < 0.05) and similar between adults and older adults (p > 0.05). Gait speed was higher in children compared to older adults, only (p = 0.031). Conclusions: Gait ground reaction forces and impulses were higher in children and similar between adults and older adults walking at a self-selected velocity.