Examining the role of Al-Hajjaj ibn Yusuf al-Thaqafi in the transformation of Iraq's economic structure during the Umayyad era is significant because his administrative, infrastructural, and economic measures, despite his historical delegitimization, had a profound impact on the economic organization of this strategic territory. As the primary center of production and revenue for the Caliphate, Iraq became the focus of targeted interventions aimed at revitalizing its economic capacities, regularizing its administrative bureaucracy, and centralizing financial resources under the control of the central government. The central question is: What impact did Al-Hajjaj's economic policies and reforms in the three areas of agriculture, the fiscal system, and trade have on the economic structure of Iraq, and to what extent were these developments aligned with the Umayyad Caliphate's logic of political and fiscal centralization? The research findings, gathered through a historical method with a descriptive-analytical approach, utilizing library studies and content analysis of both ancient historical sources and contemporary research, indicate the following: In the agricultural sector, measures such as stabilizing land tenure, organizing the labor force, and developing irrigation infrastructure enhanced productive capacity. In the fiscal sector, the regularization of administrative bureaus (diwans) and the focus on the systematic collection of revenues transformed Iraq into the most significant source of financing for the Caliphate.