Lithium-sulfur (Li-S) batteries are considered promising candidates for next-generation energy storage due to their high theoretical energy density and the abundance of sulfur. However, challenges such as poor compatibility with carbonate-based electrolytes and the need for excessive electrolyte volumes limit their practical implementation. Here, we explore biocarbon derived from olive pomace, an agricultural by-product, as a sulfur host for Li-S batteries operating in carbonate-based electrolytes. We use two KOH activation methods—liquid and solid—to tailor the porosity and surface properties of the biocarbon. The solid-activated biocarbon exhibits higher surface area, micropore volume, and sp ² carbon content, promoting efficient sulfur confinement and enabling solid-state sulfur conversion. We find that electrochemical performance remains stable regardless of sulfur loading or electrolyte volume. The resulting sulfur cathodes showed excellent electrochemical performance with a discharge capacity of 850 mAh g_S ⁻¹ with a sulfur loading of 4 mg_S cm⁻² and an electrolyte-to-sulfur ratio of 5 µL mg_S ⁻¹. Remarkably, these electrodes also perform well at high current densities, delivering a capacity of 620 mAh g_S ⁻¹ at 1 C and 360 mAh g_S ⁻¹ at 5 C.