This study aims to explain the policies implemented by the European Union in the process of transitioning to a green economy. To achieve this goal, the period from the adoption of sustainable development within the union to the present has been examined. The study reveals that the European Union has taken into account the environmental problems and impacts of climate change since the 1990s and has developed long-term strategies in the axis of sustainable development and green economy. Adversely affected by the global crisis in 2008, the European Union has focused on turning the crisis into an opportunity and building a dynamic, low-carbon, resource-efficient, knowledge-based, and socially inclusive society. In this regard, it has included green investments in its rescue plan and initiated the green transformation. Firstly, the concepts of sustainable development, green economy, and green growth are explained in the study. In the second part of the study, how the European Union realized its green transformation is discussed, and the European Green Deal is examined. In the final section of the study, developments regarding climate change and the green economy within the scope of the European 2020 strategy are examined.