Electrolytic manganese slag (EMS) is acidic filter residue generated during the smelting of metallic manganese. EMS were mainly disposed by stockpiling, with a cumulative quantity of more than 160 million tons in China. Due to the presence of a large amount of easily migratory manganese ions and harmful substances such as ammonia nitrogen in electrolytic manganese slag, conventional stacking disposal posed potential environmental risks. Compared to conventional disposal methods, resource utilization not only consumed large amounts of stockpiled EMS but also created economic value and environmental benefits. This study investigated the green low-carbon potential of using EMS to replace coarse aggregates in the production of ready-mixed concrete. By employing life cycle assessment (LCA) and carbon footprint analysis (CFA), the study quantitatively evaluates the resource, environmental, and low-carbon characteristics of using EMS in the production of ready-mixed concrete. The results show that the greenhouse gas emissions in scenario 2 reduced by approximately 19.25% compared to that in scenario 1 in low-carbon dimension. In the environmental dimension, scenario 2 outperformed scenario 1 in terms of ozone formation, ionizing radiation, and terrestrial acidification, but slightly underperformed in ecological toxicity and human toxicity indicators. In the resource dimension, scenario 2 reduced mineral resource depletion, fossil energy depletion, and water resource depletion by 89.09%, 17.87%, and 59.65%, respectively.