Injecting carbonated water (CWI) could be an alternative to the carbon dioxide (CO2) injection method. Within CWI, carbon dioxide is in a dissolved state rather than a free phase. This dissolution leads to elevated water density and viscosity compared to standard conditions. This experimental study utilizes a lab-synthesized thermally stable and salinity-tolerant Tetrapolymer employed as a durable mobility-modifying agent for the designed slug while delaying the release of CO2. In addition, Zinc Oxide Nanoparticles (ZnO NPs) were added to effectively alter the wettability of oil-wet rock grains and provide adsorption sites for CO2 in the porous media. A comparative analysis is presented with a commercial polymer, Polyacrylamide (PAM), regarding ambient and HPHT interfacial tension, contact angle, Zeta seizer, and zeta potential studies. The results of this investigation indicate that the polymer and ZnO nanoparticles, under optimal conditions, provide the most potent solution for the IFT reduction and contact angle studies. For the HPHT condition, the transfer of CO2 from water to oil continues, and the newfound phase gains weight, concurrently reducing the interfacial tension (IFT) between the oil and the newly formed gaseous phase due to CO2 diffusion. It also improves the diffusion rate of CO2 at the interface, promoting CO2 leaving the interface and weakening its accumulation behavior. This performance evaluation and mechanistic interpretation of a complex hybrid ZnO NPs enhanced-polymeric CWI slug promises a substantial, sustainable solution for reducing the carbon footprint while improving the oil recovery from mature sandstone formations.