Li4Ti5O12 (LTO) has been a great subject in lithium-ion battery research due to its high safety and electrochemical stability. However, the exploration of novel doping strategies to enhance its electrochemical performance remains a topic of interest. While single doping strategies have been widely investigated, co-doping strategies involving multiple dopants have only received limited attention. Here, we investigate the performance improvement of LTO through an Mg- and Fe-co-doping strategy. Fe precursors derived from steel manufacturing waste were used as dopants. Experimental results reveal that the co-doped samples exhibit enhanced capacity, cycleability, and rate capability. The theoretical analysis also provides valuable information on the electronic and structural changes induced by Mg- and Fe-co-doping, elucidating the impact on lithium-ion diffusion and storage. This approach contributes to the sustainable utilization of industrial waste and offers a low-cost method for the improvement of electrode materials. © 2024