The paper deals with the peculiarities of functioning and quality assurance of educational activities of higher education institutions under the conditions of the legal regime of martial law. It was found out that the educational sector has suffered devastating consequences as a result of Russia's full-scale invasion of Ukraine, which consist in colossal losses, material damage and intangible harm, which negatively affects the quality of educational services, and therefore the future professional and scientific potential of the country. The article has outlined the main challenges facing the system of higher education as a result of Russian aggression: destruction of educational infrastructure, a marked limiting of funding, shortage and a sharp reduction of personal potential, decrease in the number of the contingent of applicants for higher education, loss of educational management in the territories that are under temporary occupation or are in the zone of active military operations. The institutional and normative support of the educational process under martial law has been disclosed. According to the key research results the main priorities of higher education institutions in the conditions of war are the creation of a safe educational environment, the introduction of innovative approaches to the organization of the educational process, psychological support for participants in the educational process, the restoration of educational infrastructure, the continuation of intra-system transformative processes in the organization of the educational process and qualitative transformations in the system of internal quality assurance for the provision of educational services to future specialists. Reached conclusions are based on the main transformational changes in the activities of higher education institutions and also on key challenges and ways to overcome them in the context of ensuring the quality of educational services in the war and post-war periods of Ukraine's recovery.