Over the past two decades, Turkey's foreign policy toward Iran has displayed a persistent pattern of simultaneous cooperation and strategic competition. Even at critical geopolitical junctures, Ankara has avoided severing its engagement with Tehran while simultaneously competing with Iran over major regional crises. This apparent paradox raises an important question: How has Turkey's strategic culture shaped both continuity and change in Turkey's foreign policy toward Iran? Drawing on the strategic culture framework, this study employs a qualitative explanatory–analytical approach to examine Turkey's policy choices toward Iran across critical junctures. The findings show that Ankara adopts a compartmentalized approach, managing different policy domains separately to prevent tensions in one area from spilling over into others. At the same time, Turkey has preserved the core elements of its strategic culture, including a strong commitment to strategic autonomy and multidirectional diplomacy. Rather than fundamentally transforming these enduring orientations, successive regional crises have prompted their selective reinterpretation in response to changing security imperatives. Consequently, while maintaining its long-standing strategic ties with the West, Turkey has increasingly emphasized strategic autonomy, diversified partnerships, and issue-based pragmatism in its foreign policy toward Iran. The article's principal contribution is the development of a three-stage analytical model linking threat perception, the redefinition of strategic interests, and the selection of foreign policy instruments, thereby providing a systematic explanation for both continuity and change in Turkey's foreign policy toward Iran.