Although the surface area of graphene oxide (GO) is lower than that of reduced graphene oxide (rGO), the amount of carbon dioxide adsorbed on GO is higher compared to graphene or rGO. According to the Lerf-Klinowski model, GO contains hydroxyl, epoxide, carbonyl, and carboxyl groups on its edges and basal planes, which strongly bind carbon dioxide molecules, even leading to chemisorption. In this study, we explored the correlation between carbon dioxide sorption affinity and oxygen content in GO by applying oxygen plasma/UV ozone and thermal treatments. The variation in oxygen content was confirmed using XPS and FT-IR analysis. Interestingly, the trend of carbon dioxide sorption in GO was not directly proportional to the overall oxygen content. XPS peak analysis revealed that carbonyl groups significantly contribute to carbon dioxide sorption. These findings provide insight into the intrinsic properties of GO and its potential applications in carbon capture and gas storage.