Normative transitions between educational settings can be important life events for young people, having the potential to influence mental health trajectories across the life course. Interventions to target transitions have been used to support children and young people as they transition between school settings, but there is limited synthesis of their effects. Seven databases were searched to identify studies of universal interventions focused on supporting mental health and wellbeing across three main types of educational transition: preschool to elementary school; school to school (including elementary to middle; middle to high and other combinations depending on country); and high school to post-compulsory education. Effect directions for behavioural, psychological/emotional and social measures of mental health were extracted for each study and synthesized using effect direction plot methodology. Searches identified 6494 records for screening. This resulted in 34 papers being included in the review, consisting of 24 different interventions. Social outcomes appeared more amenable to intervention than behavioural outcomes, with mixed findings for psychological measures of mental health. Intervention characteristics shifted based on the age of young person involved in the transition, with greater focus on parenting and school environment during the early transitions, and more focus on social support for the transition to post-compulsory education. A broad range of interventions were identified for supporting mental health and wellbeing across the three types of educational transition with mixed impact and diverse methodologies. More research is needed to identify transferable intervention mechanisms that may hold across different contexts and settings.