This study evaluated the feasibility and potential efficacy of a family-based intervention to improve physical activity (PA) and fundamental movement skills (FMS) in preschoolers and modify parenting PA behaviors by using a cluster randomized controlled trial. Underpinning the social cognitive theory, the components of the intervention included parental workshops, FMS training, PA homework, and equipment provision. 108 parent-child pairs from five preschools were allocated to intervention or wait-list control groups. The 8-week intervention had positive effects on children's moderate-to-vigorous physical activity (MVPA) and FMS proficiency. It also improved parental self-efficacy, goal setting, supportiveness, and co-participation in PA, but not parental PA levels. The current insights can inform initiatives to establish an active social environment for young children.