The present article aims to systematically summarize the effects of free-play (FP) on preschool-aged children's physical activity (PA) level, and motor (MC), cognitive (CC), and socioemotional competence evaluated through randomized controlled trial (RCT) design. A systematic review of relevant articles was carried out using two electronic databases (PubMed, Web of Science) until 19 October 2022. From a total of 674 studies initially found, 16 were included in the qualitative synthesis. The general outcomes suggest that FP, together other methodologies, may foster MC rather than FP by itself. However, other methodologies have shown greater positive effects than FP for improving PA level, CC, and socioemotional competence. Therefore, the implementation of FP methodology rather than others (e.g. structured play) is not supported by published RCT, at least, when it is not implemented with another methodology.