There is an urgent need for the mitigation of climate change through CO₂ reduction technologies. In this work, we demonstrate a novel method for production of porous graphene-like nanosheets (PGLNS) from the lignocellulosic fiber of oil palm empty fruit bunches (EFB) by a thermal graphitization technique for efficient CO₂ capture. We used a wide range of microscopic and spectroscopic techniques to provide insights into the morphological and structural characteristics of the synthesized PGLNS (with d-spacing of ∼0.35 nm and pore size of <1 nm) obtained from the EFB biomass. The PGLNS show excellent performance as adsorbents for post-combustion CO₂ capture. At 25 °C and 1 bar pressure, the maximum CO₂ uptake was 2.43 mmol g⁻¹ which is considerably higher than other competitive CO₂ adsorbents, including zeolite, activated carbon and some metal organic frameworks. The selectivity of the PGLNS for CO₂ over N₂ (S_CO2/N2 = 18.7), computed from single component isotherms at conditions pertinent to post-combustion applications, is also much higher than that of most of the previously reported adsorbents. Moreover, the significantly low isosteric heat of adsorption (∼21 kJ mol⁻¹) revealed the possibility of desorbing CO₂ and regenerating the PGLNS for their repeated use at a much lower energy penalty.