Background: The key role of medical workforce well-being in the delivery of excellent and equitable care is recognised internationally. However, doctors are known to experience significant mental ill health and erosion of their well-being due to challenging demands and pressurised work environments. Existing workplace support strategies often have limited effect and do not consider the multiple factors contributing to poor well-being in doctors (e.g. individual, organisational and social), nor whether interventions have been implemented effectively. Aim: To work with, and learn from, diverse hospital settings to understand how to optimise strategies to improve doctors’ workplace well-being and reduce negative impacts on the workforce and patient care. Design and method: Three inter-related sequential phases of research activity: • Phase 1: a typology of interventions and mapping tool to improve hospital doctors’ workplace well-being based on iterative cycles of analysis of published and in-practice interventions and informed by relevant theories and frameworks and engagement with stakeholders. • Phase 2: realist evaluation consistent with Realist And MEta-narrative Evidence Syntheses: Evolving Standards quality standards of existing strategies to improve hospital doctors’ workplace well-being in eight purposively selected acute National Health Service trusts in England based on 124 interviews with doctors, well-being intervention implementers/practitioners and leaders. • Phase 3: codeveloped implementation guidance for all National Health Service trusts to optimise their strategies to improve hospital doctors’ workplace well-being – drawing on phases 1 and 2, and engagement with stakeholders in three online national workshops. Results: • Phase 1: although many sources did not clarify their underlying assumptions about causal pathways or the theoretical basis of interventions, we were able to develop a typology and mapping tool which can be used to conceptualise interventions by type (e.g. whether they are designed to be largely preventative or ‘curative’). • Phase 2: key findings from our realist interviews were that: (1) solutions needed to align with problems to support doctor’s well-being and avoid harm to doctors; (2) involving doctors in creating solutions was important to address their well-being problems; (3) doctors often do not know what well-being support is available and (4) there were physical and psychological barriers to accessing well-being support. • Phase 3: our ‘Workplace well-being MythBuster’s guide’ provides constructive evidence-based implementation guidance, while authentically representing the predominantly negative experiences reported in phase 2. Limitations: Although we sampled for diversity, the eight trusts we worked with may not be representative of all trusts in England. Conclusions: Misaligned well-being solutions can cause harm. It is paramount to prioritise improvements in working environments, instead of well-being ‘add-on’s, and to involve doctors and other relevant staff in identifying problems and in planning how to address these. Future work: Further research is required to tailor the findings to primary care, mental health and social care settings. Health economic studies of well-being interventions (ideally, at systems level) are urgently required, since small investments could have far-reaching positive impacts.