United Kingdom (UK) public health policy increasingly emphasises integrated, community-based whole-system approaches that prioritise social prescribing to promote mental wellbeing and support individuals awaiting formal clinical services. While yoga is known to improve personal wellbeing, its specific social value remains under-researched. This study evaluated the social impact of a five-week Dru Yoga Wellbeing (DYW) Programme for UK participants with mild-to-moderate mental health challenges.Adopting a Social Return on Investment (SROI) framework, this study evaluated a five-week social prescribing intervention. The programme was developed through a collaborative design process with nine regional instructors to ensure local relevance and then subsequently delivered across nine UK locations between July and October 2025. Quantitative outcomes (n = 59; 41 complete cases) were monetised via the UK Social Value Bank and UK Mental Wellbeing Bank. To provide a holistic perspective, the quantitative data were triangulated with qualitative insights from questionnaires (n = 40) and semi-structured interviews (n = 9), which were analysed using a thematic biopsychosocial framework. The SROI analysis for the DYW Programme adhered to the standard Cabinet Office methodology, incorporating adjustments for deadweight, attribution, displacement, and drop-off to ensure the robustness of the findings.Quantitative analysis revealed substantial pre- to post-intervention improvements across all measured outcomes, including life satisfaction, mental wellbeing, and anxiety reduction. Qualitatively, thematic analysis identified key biopsychosocial outcomes: psychological improvement, enhanced social connection, and improved physical wellbeing. Qualitative data provided a deeper narrative of how the programme mitigated anxiety and increased wellbeing.Overall, the DYW Programme delivered a positive return on investment, generating between £3.11 and £3.60 in social value for every £1 spent. The alignment of quantitative SROI ratios with qualitative biopsychosocial outcomes suggests the programme can be a high-value preventative service, well-suited for integration into regional social prescribing pathways. By shifting the focus from clinical pathology toward participant empowerment, the DYW Programme applies community psychological principles to support local mental health.