A carbon matrix with an appropriate porous structure plays a vital role in developing high-performance sulfur/carbon cathodes of lithium–sulfur batteries. In this work, a hierarchical porous carbon fiber (HPCF) with a few mesopores and abundant micropores was prepared via electrospinning with a SiO₂ template and subsequent KOH activation. The HPCF with an ultra-high surface area and a large pore volume can construct a loose network structure to promise high sulfur utilization and sufficient sulfur loading. Mesopores can provide pathways for the infiltration of electrolyte to ensure fast transport of lithium ions during electrochemical reactions, whereas micropores can effectively suppress the diffusion of polysulfides by their strong adsorption capability. Due to such advantages, the proposed cathode, with 66 wt% sulfur content, can yield a high reversible capacity of 1070.6 mA h g⁻¹ at 0.5C, and a stable cycle performance with a capacity retention of 88.4% after 100 cycles.