OBJECTIVES: Diagnostic errors represent the most common and costly preventable patient safety events, with historically marginalized populations disproportionately impacted due to systemic inequities in healthcare. Addressing these disparities requires embedding equity into every facet of the diagnostic process. The aim was to develop, refine, and validate a competency framework for Equity-Driven Diagnostic Excellence (DxEqEx). METHODS: A modified Delphi method was used, involving transdisciplinary diverse healthcare system participants, including patient advocates, physicians, nurses, and other healthcare professionals. Participants were guided through multiple rounds of feedback and ratings, assessing the importance, disciplinary relevance, feasibility, skill acquisition level required, granularity, and representativeness of the DxEqEx framework. RESULTS: Sixteen essential competencies have been identified, categorized into three domains: Intrapersonal, Team-based, and Structural. Participants rated the framework with high importance and strong relevance to their respective disciplines. However, the feasibility of implementing the framework varied, largely due to broader challenges within the healthcare system. The competencies were assessed as requiring a proficient skill level according to Dreyfus' model. The final round maintained strong ratings for granularity and representativeness, which supported the final version of the framework. CONCLUSIONS: The DxEqEx framework holds significant potential to proactively address the needs of historically marginalized patients throughout the diagnostic process. Future research should focus on participatory, resource-efficient implementation.