The EU’s aspirations for leadership are also evident in regional and global climate policy, especially given the urgency of the problem of rising global temperatures. Since 2014, EU member states have been actively involved in shaping the organisation’s legislative framework on climate policy. This article set out to determine when the EU gained the capability to act as a normative green power and to assess whether the EU acted as an established normative power in forming a climate partnership with Ukraine from the 1990s to the first half of 2024. The research is organized into two chapters. Chapter 1 explores two dimensions of the behavioral logic of different foreign policy actors: norm compliance and norm diffusion. Normative actors of foreign policy, unlike non-normative ones, are guided by the logic of appropriateness in the process of compliance with norms and the logic of argumentation in the process of diffusion of norms. Chapter 2 identifies the periods when the EU complied with climate norms according to the logic of appropriateness and spread climate norms in Ukraine according to the logic of arguing. After analyzing two dimensions of the EU’s behavioral logic in detail, it can be concluded that it was only after 2019 that the EU began to act as an established normative power in building a climate partnership with Ukraine. In other words, from this point onward, the EU both complied with climate norms according to the logic of appropriateness and diffused them in Ukraine according to the logic of arguing. The European Climate Law, enacted in 2021, further demonstrated the EU’s dedication to complying with climate norms based on the logic of appropriateness, establishing legislative obligations to achieve climate neutrality by 2050.