One approach within the Islamic camp treats Islam, which emphasizes overarching notions such as the ‘Islamic brotherhood’ and ‘ummah’, as incompatible with ethno-nationalist ideas and movements. It is, however, striking that in the last decades, several Islamic and conservative groups in Turkey have paid increasing attention to the Kurdish issue, supporting their ethnic demands and sentiments. Even more striking, the leftist, secular Kurdish ethno-nationalists have adopted a more welcoming attitude toward Islam. How can we explain such intriguing developments and shifts? Using original data derived from several elite interviews and a public opinion survey, this study shows that the struggle for Kurdish popular support and legitimacy has encouraged political elites from both camps to enrich their ideological toolbox by borrowing ideas and discourses from each other. Further, Turkish and Kurdish nationalists alike utilize Islamic discourses and ideas to legitimize their competing nationalist claims. Exploring such issues, the study also provides theoretical and policy implications.