Purpose In pursuit of objectives, under the European Green Deal, to channel capital flows to sustainable activities, the EU Taxonomy offers clarity, labelling real economic activities as “sustainable”, based on technical screening criteria. This study of disclosure experiences aims to explore the role of co-evolutionary relationships in the Taxonomy’s effectiveness. Design/methodology/approach Co-evolution theory implies a dynamic interplay among sustainable finance stakeholders (SFSs), through adjustment to, impact on and operationalisation of the Taxonomy. Corporate disclosure experiences, including those of financial institutions and related SFS experiences, may reveal co-evolutionary processes. With significant Undertakings for Collective Investment in Transferable Securities (UCITS) and Alternative Investment Funds (AIFs), Irish SFSs provide contextual insight. Semi-structured interviews with a purposive sample of Irish SFSs capture inaugural corporate Taxonomy disclosure experiences. Findings A thematic analysis reveals six co-evolutionary processes that facilitate Taxonomy implementation in pursuit of policy objectives: [1] cross-functional reporting; [2] iterative pre-empting and addressing compliance issues; [3] regulation as a catalyst for co-evolution; [4] advanced capacity building; [5] stakeholder adaptation and [6] graduated use of ESG data. Implications for sustainability policy development and management are significant. Practical implications Whilst limited to just one EU jurisdiction, given limited prior empirical evidence for sustainable finance regulations from co-evolutionary perspectives, this study highlights a catalytic, yet precautionary role for co-evolution in their transformation effectiveness. As such, they must take account of their potential to stimulate co-evolution and to nurture it in pursuit of their policy objectives. Social implications The findings of this study add to a small, but growing body of academic literature on the Taxonomy Regulation, which suggests that a co-evolutionary lens is important for gaining a comprehensive understanding of its early-stage dynamics. From an implementation perspective, the qualitative data reveals actionable implications for regulators and policymakers, such as building capacity, better anticipation of outcomes and investment in data infrastructure. Originality/value Unlike existing analyses of disclosures, this study offers a co-evolutionary lens on Taxonomy contributions to sustainable development through qualitative accounts.