This study examined the effects of a combined virtual-reality- and gym-based physical activity (PA) program on PA levels, motor skills, and social skills of children with a developmental disability (DD). Twenty-five children with DD were randomly assigned to experimental and control groups. The intervention was conducted for 60 min, two times a week, for 12 weeks. Pre- and postintervention assessments encompassing PA levels measured via Gravity Estimator of Normal Everyday Activity, motor skills evaluated using the Test of Gross Motor Development-Third Edition, and social skills gauged via the Social Skills Rating System-Parent were conducted. Additionally, a follow-up assessment was administered to the experimental group 12 weeks postintervention. The findings unequivocally demonstrate that the combined virtual-reality- and gym-based PA program yielded significant enhancements in PA levels, motor skills, and social skills among children with DD in the experimental group. Notably, these improvements were sustained 12 weeks after the intervention. These findings may help professionals develop and implement better PA programs for children with DD.