This chapter analyses the core values of the European Union (EU) as a key precondition for EU membership and the legal mechanism of their implementation in the legal order of Ukraine. The authors analyse the content of the written and unwritten criteria for EU membership and compare them with the core values enshrined in Article 2 of the TEU: human dignity, freedom, democracy, equality, the rule of law and respect for human rights, in particular those of persons belonging to minorities. The authors also examine the normative content of the duty to respect and promote values. The accession procedure and its impact on the implementation of values by the candidate country, as well as the significance of other EU instruments designed to prepare for accession and their impact on the implementation of values by the candidate country are also examined (Association and Stabilisation Agreements, IPA III, Twinning, TAIEX, TASCO, SIGMA). The final section analyses the main reforms carried out by Ukraine to implement EU values, in particular in the field of media, the fight against corruption and protection of national minorities. Restrictions on constitutional rights and freedoms in connection with the introduction of martial law are examined for compliance with Ukraine’s international legal obligations. The authors investigate the state of implementation of EU values in the constitutions of Ukraine and in the judicial practice of Ukrainian courts. Recommendations are also formulated to improve the implementation of EU values in the legal system of Ukraine.