Health inequities are not inevitable. Coordinated policy action on the determinants of health combined with well designed and implemented governance approaches have a dual effect on reducing the health gap and improving overall population health. This guide is the first product developed under Public Health Wales’ WHO Collaborating Centre (WHO CC) on Investment for Health and Well-being work programme and outlines four key phases on how to synthesize, translate and communicate public health economics evidence into policy and practice. The interrelated four phases guide the reader through the process of developing evidence-informed products, which are context and target audience specific. The guide aims to (i) prevent disinvestment in health; (ii) increase investment in prevention (public health); and (iii) and mainstream cross-sectoral investment to address the wider determinants of health and equity, driving sustainable development for prosperity for all. It has been developed based on a mixed-method approach including an evidence review, interviews with national and international experts, and a multisectoral stakeholder consultation which ensured relevance and transferability across sectors, contexts, settings and countries.