The hybrid sorbent, combining ionic liquid and activated carbon, offers an innovative pathway for CO₂/CH₄ separation. This study prepared three single-step steam activated bamboo carbons (SBCs), and developed the hybrid sorbents of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Hmim][NTf₂])/SBCs/water (H₂O). The gas solubility and sorption rate in the hybrid sorbent were measured, and the Henry's constant, selectivity, and liquid-phase mass-transfer coefficient were calculated. Additionally, a self-developed index was utilized to estimate the CO₂/CH₄ separation cost using the hybrid sorbents. The results showed that the hybrid sorbent containing SBCs prepared by the steam activation at 1073.2 K and 120 min (S812) exhibited the most efficient CO2/CH4 separation performance owing to its optimal microporous structure and oxygen-containing functional groups. Consequently, the hybrid sorbent of [Hmim][NTf₂]/S812-H₂O (w_{[Hmim][NTf2]/S812}=3.0 wt%) demonstrated a 3.2 times intensification on the comprehensive CO₂/CH₄ separation performance as well as a 53.8 % reduction of separation cost compared to the commercial technology.