<p>Mineral resources development involves a series of activities, including drilling, blasting, loading, hauling, crushing, and grinding for liberating valuable minerals. Blasting is the primary activity to fragment the ore body, which significantly influences the efficiency of all downstream activities. Reducing the fragment size can reduce the energy consumption of crushing and grinding. Therefore, the mine-to-mill (M2M) method integrating mining and mineral processing into blast fragment size optimization is considered as an effective strategy for saving cost. All the activities in metal mines are high carbon emissions. Under the carbon pricing policy, it is necessary to consider the influence of carbon emission to optimize the open-pit mine design. In this study, an improved M2M method considering the carbon emissions is proposed to determine the optimal mean blast fragment size (<i>x</i>₅₀) for cost reduction. A series of carbon emission and cost formulas for each activity is derived with <i>x</i>₅₀ as the independent variable. Taking the Uragen open-pit mine as an example, the optimum process by the proposed method is illustrated and the influence of carbon pricing on optimal <i>x</i>₅₀, economic performance, and potential cost savings is discussed. This study provides a technical solution for cost optimization in open-pit mining under carbon pricing.</p>