This systematic review protocol outlines the background, methodology and inclusion and exclusion criteria for a systematic review of how effective are school-based wellbeing interventions for improving the academic and non-academic outcomes of children and young people in mainstream schools? The proposed systematic review will be conducted in accordance with the Joanna Briggs Institute methodology for systematic reviews of effectiveness evidence. It will complement system-wide strategic imperatives for health and wellbeing promotion by providing robust evidence to inform policy and practice supporting student wellbeing. The review will only involve interventions that report impact on academic achievement for a population of students in mainstream schools between 5 and 18 years, who receive an intervention in the mainstream school setting. This includes children with learning difficulties. The review will consider experimental, and quasi-experimental designs including randomised and non-randomised controlled trials, where a comparison group are involved.