Due to their exceptional electrochemical properties, lithium-sulfur batteries are regarded as one of the most promising candidates for energy storage systems. Yet, their commercialization is significantly hindered by severe shuttle effects and sluggish redox kinetics. Herein, a highly ordered mesoporous TiO2 (OMT) material with atomic-level Nb doping (Nb-OMT) was innovatively constructed as a bifunctional electrocatalyst, enabling superior performance in lithium‑sulfur (LiS) batteries. Density functional theory (DFT) calculations confirm that Nb doping could effectively enhance the electrical conductivity of the mesoporous TiO2, facilitating simultaneous adsorption and catalytic conversion of lithium polysulfides (LiPSs) on the material surface, thereby accelerating sulfur redox kinetics. Therefore, the LiS cell with Nb-OMT-20 modified separator demonstrates an exceptional specific capacity of 1348.9 mAh g-1 in LiS batteries at 0.2C, meanwhile exhibiting an ultralow capacity decay rate of merely 0.036% per cycle over 900 cycles at 1C. Notably, even under challenging conditions, including a high sulfur loading of 5.12 mg cm-2 and a low temperature of 273 K, the LiS battery still delivers a considerable capacity of 1146.1 mAh g-1 at 0.1C with a capacity retention of 83.4% of its capacity over 100 cycles at 0.2C, suggesting promising potential for practical applications. This work presents a novel approach to developing bifunctional electrocatalysts through atomic-scale structural modulation, thereby advancing the industrial application of LiS batteries.