This research aims to analyze the resilience of Indonesia’s copper ore reserves in supporting sustainable copper cathode production targets, in line with national downstream policies. Using a quantitative approach, this study evaluates secondary data from national mineral reserve reports and the production capacity of major smelters. The analysis is conducted by calculating the reserve-to-production ratio to project mine life under three scenarios of increasing domestic refining capacity, including an aggressive scenario of 1.145 million tons per year. The results indicate that based on current reserves, the estimated mine life is approximately 21 years under maximum production capacity. However, with potential resource-to-reserve conversion of approximately 4.318 billion tons and accounting for ore grade decline, the life of Indonesia’s copper ore reserves is projected to extend until 2077. The study also reveals a structural gap, where 70% of cathode production is still export-oriented due to low domestic manufacturing absorption. The uniqueness of this paper lies in the integration of geological reserve aspects with the dynamics of downstream policies and industrial structure theories. Practically, this study provides important implications for the government in formulating strategic reserve management and emphasizes the urgency of integrating upstream smelting with downstream manufacturing to ensure long-term industrial sovereignty.