Lithium–sulfur (Li-S) batteries hold great promise for next-generation energy storage, offering high theoretical energy density and cost-effectiveness. However, challenges like sulfur’s low conductivity, polysulfide dissolution, and significant volume changes limit their practical application. This study addresses these issues by investigating porosity-engineered carbon hosts, specifically potassium hydroxide (KOH)-activated Black Pearl carbons (BP2000, BP1300, and BP800). Varying KOH-to-carbon ratios allowed precise tailoring of micro- and mesoporous structures, optimizing sulfur loading, electrolyte infiltration, and ion transport. Composites were characterized by TGA, NLDFT, SEM, XRD, and FTIR and electrochemically (cycling, CV, EIS). The KOH-modified BP2000 1:1 cathode, exhibiting the highest mesopore volume increase, demonstrated superior electrochemical performance, including enhanced cycling stability, rate capability, and reduced charge-transfer resistance. These findings emphasize the importance of optimizing pore distribution in carbon hosts for high-performance Li-S batteries and provide valuable insights for advanced energy storage material design.