The article examines the ideological and attitudinal prerequisites of the international cooperation between Irish leftist nationalists and the RSDLP (Bolsheviks) in 1916–1917. It describes the historical aspects characterizing the essence of the ideological orientations of Ireland’s national liberation organizations at the beginning of the 20th century within the context of the RSDLP (Bolsheviks) international agenda during 1916–1917. The analysis draws upon lesser-known domestic sources from the 1910s, some of which are introduced into scholarly discourse for the first time. The author expresses the opinion that during this period, Bolshevik leaders, particularly V.I. Lenin, I.V. Stalin, and L.D. Trotsky, placed considerable hopes on the socialist awakening in Ireland. For the international communist movement, Britain remained the primary imperialist predator, and the struggle against global imperialism continually shaped the political agenda in Soviet Russia. The article notes the existing Bolshevik viewpoint on the Irish question in international affairs during those years, according to which Ireland’s movement against English imperialism represented a progressive social process and therefore needed to be supported through both overt and covert means. In conclusion, the article sheds light on the intricate dynamics of international collaboration between Irish leftist nationalists and the RSDLP (Bolsheviks) during the pivotal years of 1916–1917. Overall, it enriches scholarly discourse by offering a comprehensive analysis supported by primary sources, normative-legislative base, and representative literature.