Introduction: Globally, 8%–14% of children and young people (CYP) have a diagnosable mental health condition, many of whom receive no formal interventions. Parents/carers of CYP experience stress and distress owing to the mental health difficulties encountered by their CYP due to the lack of resources and support. Currently, little is known about (1) the content of interventions developed to support parents/carers nor (2) how effective interventions are at improving parents’/carers’ well-being. The planned review aims to address these two gaps. Method and analysis: A systematic review will be conducted to identify any study that describes an intervention aiming at least in part to support parents/carers with the impact of CYP (5–18 years) mental health difficulties, and to review any randomised controlled trials (RCTs) of these interventions. The following databases will be searched: MEDLINE, PsycINFO, CINAHL, AMED, EMBASE, Web of Science Core Collection and Cochrane Library CENTRAL, without any limitations applied. Analysis of the content of interventions will be structured using the Template for Intervention Description and Replication checklist as a framework. The effect of any RCTs on parents’/carers’ outcomes (including well-being, satisfaction with parenting, mental health) will be extracted and assessed using the Cochrane Risk-of-Bias Tool. Data will be synthesised narratively, with meta-analysis of RCT results, if appropriate. Ethical consideration and dissemination: The protocol is approved by Coventry University Ethical Committee (reference number: P139611). Results will be shared in academic publications and in accessible formats using social media and public webinars. PROSPERO registration number: CRD42022344453.