Russia's full-scale war against Ukraine actualized the issue of the identity foundations of the people of Ukraine and countering hostile anti-Ukrainian narratives. The purpose of the study was to outline the activities of Ukrainian libraries on countering the spread of Russian national myths and narratives, disclose presented in library space of Ukraine complex of suitable for construction of the Ukrainian strategic narrative key ideas and meanings, which reflect the Ukrainian community's mythologized ideas about itself, its place in the world and its prospects. An anthropological approach, methods of systematization, critical discourse analysis, discussion, external and included observation are applied. Related to the documented historical and cultural heritage key meanings, reflecting the Ukrainian community's mythologized ideas about itself, its place in the world and its prospects, suitable for constructing the Ukrainian strategic narrative and providing the spiritual and value basis of the national idea of the people of Ukraine were defined. It was revealed that decolonization of the library information space, publishing, socio-cultural, and educational activities of Ukrainian libraries in the conditions of the Russia's full-scale war against Ukraine are aimed at debunking such Russian national myths and narratives, as myths about “one people” and “one cradle – the ancient Rus’ state”, “the Great Victory” and the Great Patriotic War, the USSR as a country of prosperity. It was proved that libraries' efforts are directed to the forming and strengthening the informational resilience of users, establishing nation-affirming values and meanings landmarks related to the struggle of the people of Ukraine for freedom, statehood and independence, to periods of national elevation (the Kyivan Rus’ age, the Lithuanian-Polish period, the Ukrainian State of Hetman Pavlo Skoropadsky), the life-giving force of folk traditions, the pattern of the National Renaissance, the dream of the European future of Ukraine. The obtained results will be useful in the development of state information policy, the politics of memory, and in the practical activities of libraries