Early years interventions have shown to be effective in improving the social communication and language skills of autistic children. Therefore, various play-based interventions have been developed to support those developmental areas of autistic children. Although researchers have previously reported the overall effectiveness of different types of play-based interventions on the social communication and language skills of autistic children, no previous systematic reviews have yet evaluated the effectiveness of parent-mediated play-based interventions in preschool autistic children. The overarching aims of the study will be to (i) report the key characteristics and (ii) synthesise the results of studies evaluating parent-mediated play-based interventions targeting the social communication and language skills of preschool autistic children using experimental designs. A comprehensive search for and screening of the relevant studies published between 2000 and 2021 will be undertaken. To be included, studies will have to (i) use either a randomised control trial or quasi-experimental design, (ii) focus on preschool autistic children aged six years old or younger, (iii) deliver a play-based intervention in non-educational settings, and (iv) include at least one parent as the mediator of the intervention. Data extraction of all included studies will be undertaken using a specially devised template and they will also be assessed for risk of bias using an adapted form from the Cochrane Risk of Bias tool. The overall characteristics of the included studies will be reported and a narrative synthesis of the results of the included studies will be undertaken. A meta-analysis may be performed (if justified) to report the pooled effect size of the parent-mediated play-based interventions on the social communication and language skills of preschool autistic children. Trial registration: The current study protocol was pre-registered with the international prospective register of systematic reviews (PROSPERO: CRD42022302220).