Social Return on Investment (SROI) is a methodological approach which incorporates all three aspects for evaluating interventions. Mental health problems are one of the leading causes of ill health and disability worldwide. This study aims to map existing evidence on the social value of mental health interventions that uses the SROI methodology. This scoping review is a first of its kind to focus on SROI of mental health interventions, finding a good number of SROI studies that show a positive return on investment of the identified interventions. This review illustrates that SROI could be a useful tool and source of evidence to help inform policy and funding decisions for investment in mental health and wellbeing, as it accounts for the wider social, economic, and environmental benefits of public health interventions.