Activated carbon derived from biomass sources is one of the most promising adsorbents for carbon dioxide (CO2) capture because it is inexpensive, effective, and environmentally friendly. The increment of CO2 in the atmosphere is the root cause of numerous climate change-centric environmental problems, in which one of the major CO2 emission sources is known to be the fossil-fuelled power plant. The most mature CO2 capture system (post-combustion capture) of fossil-fuelled power plants involves capturing CO2 from flue gas at low CO2 composition (5–15 wt%), with the remaining gas composed mainly of nitrogen (N2). Hence, this study investigated the effect of the CO2 and N2 gas compositions on the binary CO2-N2 adsorption performances of the activated carbon derived from pomelo peel (PP). Moreover, the comparison of the adsorption performance between pomelo peel-based activated carbon (PPAC) and commercial activated carbon (COMM-AC) was also evaluated. Besides that, PP and PPAC were also characterized through Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The results demonstrated that PPAC has a low graphitization degree and possess a microporous-mesoporous structure, with the pores mainly composed of micropores. The attained results on the effect of the gas compositions showed that higher CO2 gas composition leads to a higher binary CO2-N2 uptake, indicating that PPAC is more selective towards CO2 than N2. By comparing the adsorption performance of PPAC and COMM-AC, it was inferred that COMM-AC is a superior adsorbent at a higher pressure and CO2 composition condition. In contrast, PPAC was found to be a better adsorbent at a lower pressure and CO2 composition condition. These results signified that PPAC is a potential adsorbent for CO2 gas, especially in post-combustion flue gas conditions.