There is growing global interest in the potential for ecosystem markets to facilitate climate and nature recovery. Yet, poorly designed and operated markets are prone to corporate “greenwashing” and negative consequences for nature and local communities. With the rapid emergence of ecosystem markets around the world, there is a need to systematically analyse ecosystem market governance principles, and identify the practical steps needed to implement these principles at national scales across multiple high-integrity ecosystem markets. Markets are considered high integrity when they are governed by clear and consistent principles that address governance, measurement, reporting and verification, and wider benefits. The majority of principles published to date are designed to be applied at international scales or within single markets. However, national policy oversight is essential to ensure emerging ecosystem markets deliver natural capital outcomes and wider public benefits appropriate to the jurisdictions in which they operate. Relying on international voluntary initiatives alone is unlikely to prevent the operation of low-integrity schemes. This paper therefore analyses principles for the development and operation of high-integrity ecosystem markets, proposing how these could be operationalised to in the UK, where governments in Scotland and England are actively developing new governance regimes for rapidly proliferating domestic ecosystem markets. To do this, the paper: 1. Provides the first comprehensive overview of compliance and voluntary carbon and other ecosystem markets alongside the first analysis of relevant ecosystem market actors in the UK ; 2. Conducts a comparative analysis of existing national and international principles, identifying 14 core principles for governance, measurement, reporting and verification, and delivering wider benefits of high-integrity ecosystem markets that could be applied by relevant market actors to the range of ecosystem markets identified in the UK; and 3. Proposes how these principles could be applied in an ecosystem markets governance hierarchy, showing policy, governance and market mechanisms and infrastructure that are being developed to implement the proposed principles in the UK. Taken together, the proposed core market principles and governance hierarchy could be used to ensure the development of high-integrity ecosystem markets across the UK and internationally, helping national governments to responsibly build and scale these markets.