This monograph offers a comprehensive and critical examination of Türkiye’s constitutional trajectory from the late Ottoman Empire to the presidential regime under Recep Tayyip Erdogan. Bridging legal history, political theory, and constitutional analysis, the author interrogates the persistent tension between democratic aspirations and authoritarian consolidation in Turkish constitutionalism. Through a diachronic and thematic approach, the book traces the ideological currents of Kemalism and Erdoganism, revealing their shared roots and dissecting their divergent visions for Türkiye’s legal and political identity. It explores the evolution of constitutional texts, the role of the military and judiciary, the instrumentalization of religion and nationalism, and the contested status of minority rights and gender equality. It delves into the foundational reforms of the Tanzimat, the birth of the Republic, the oscillation between liberalization and repression, and the rise of hegemonic authoritarianism under the Adalet ve Kalkinma Partisi - AKP (Justice and Development Party). Drawing on extensive primary sources and doctrinal literature, the author situates Türkiye within broader debates on liberal-democratic constitutionalism, populism, and competitive authoritarianism. This volume contributes to the understanding of Türkiye not merely as a case of democratic backsliding, but as a polity caught in cyclical patterns of institutional rupture and ideological re-foundation. Rich in historical detail and legal insight, Constitutional Law and Politics in Türkiye: From Atatürk to Erdogan is an essential reading for scholars and students of constitutional law, comparative politics, Middle Eastern studies, and modern Turkish history, and readers interested in understanding the complex interplay of law, ideology, and power in one of the world’s most geopolitically pivotal nations.