After the Lisbon Treaty, the European Union (EU) has prioritized sustainable development as a key aspect of its external trade and investment policy. This emphasis on sustainability has been reinforced through treaty- making and has received support from the Court of Justice of the European Union (cjeu). However, there are notable variations and nuances in the understanding and implementation of sustainability in the EU’s treaties. Moreover, these treaties introduce innovative dispute resolution mechanisms, such as arbitration and alternative dispute resolution methods, which can significantly impact international dispute settlement practices. Opinion 2/ 15 on the EU- Singapore Free Trade Agreement marked a crucial moment in clarifying the scope and nature of sustainable development chapters within the EU’s trade and investment policy. Different agreements concluded after the Lisbon Treaty reflect diverse approaches to sustainability. In the context of environmental protection, these agreements encompass a range of provisions, from generic to more specific clauses addressing particular aspects. This article critically analyzes the effectiveness and scope of “green conditionality” within the Sustainable Development Chapters of EU-established Trade and Investment Agreements. It examines the incorporation of environmental provisions in these agreements, evaluates their role in promoting sustainable development objectives, and explores the implications of dispute settlement and international arbitration mechanisms. This analysis aims to provide a cutting- edge perspective on the topic.