<p>As the second most important by-product of the coking industry after coke, coke oven gas (COG) has long been a key focus of research in the field. The technology of injecting COG into blast furnaces has gained widespread attention and industrial application in the steel industry due to its significant energy-saving and emission-reduction benefits, which include reducing solid fuel consumption and lowering CO₂ emissions. This study constructs a model of the blast furnace hot metal production system based on the Life Cycle Assessment (LCA) method. It quantitatively analyzes the evolution of environmental impacts from COG injection, with a particular focus on its influence on carbon footprint, and conducts a sensitivity analysis of key influencing factors. The results indicate that COG injection significantly reduces the global warming potential, resource depletion, and non-carcinogenic ecotoxicity associated with molten iron production. Increasing the COG injection rate from 0 to 80 m³/t reduced the life cycle CO₂ emissions of hot metal from 1731.24 kg/t to 1627.81 kg/t. This net reduction resulted from decreased indirect emissions in the coking process (from 198.21 kg/t to 120.92 kg/t, a 39.00% decrease) and the sintering process (from 627.41 kg/t to 599.45 kg/t, a 4.46% decrease), which outweighed a 4.29% increase in direct emissions from the blast furnace (from 907.54 kg/t to 946.49 kg/t). Furthermore, sensitivity analysis identified coke consumption as the most influential factor governing CO₂ emissions in this process.</p> Graphical Abstract <p></p>