The chapter delves into the legal implications of agri-environment-climate commitments within the European Union (EU) agricultural law framework, focusing on implementing Payment for Ecosystem Services (PES) mechanisms. The chapter traces the evolution of agri-environmental measures under the Common Agricultural Policy (CAP) from the mid-1980s to the present, highlighting their role in integrating environmental objectives into agricultural practices through results-based commitments. These commitments are mandated by successive regulations, emphasizing the EU’s dedication to sustainable agriculture. Additionally, the chapter addresses the challenges associated with results-based agri-environment-climate commitments. By analyzing the legal frameworks, contractual arrangements, and implications of results-based agri-environment-climate commitments, this chapter provides a comprehensive overview of the legal mechanisms supporting ecosystem services in EU agriculture, thereby contributing to the discourse on sustainable agricultural practices and environmental governance.