Enhancing oil recovery (EOR) using a polymer is commonly used as a tertiary recovery to enhance the production of oil felids that have reached depletion in oil production. It is known that the sensitivity of the polymer in the harsh environment of the reservoir due to the high salinity and high temperature weakens the performance of the polymer in EOR such as poor injectivity, poor sweep efficiency, and gravity override. However, Nanotechnology could be one of the new techniques that help to overcome the challenges that face the polymer in CEOR. This study evaluated new aqueous polymeric nanofluid to investigate how effectively it performed when exposed to different temperatures, salinities, and aging times to improve the performance of chemical EOR. The polymer used in this study was HPAM with a hydrolysis level of 40% and a molecular weight of 10 MD. This study's objectives are to improve the performance of a polymer HPAM by upgrading rheological characteristics using a multi-walled carbon nanotube functionalized with -COOH (MWCNT-COOH). Synthesized polymeric nanofluid and its performance will be evaluated through several temperatures and salinities. The Polymeric nanofluids will be characterized by using the subsequent methods. First, to detect the bonding of the polymeric nanofluid, the FTIR (Fourier Transform Infrared spectrometer) test will be performed. Then, to study the viscoelastic behavior of polymeric fluids, which is the most essential property, both static and dynamic shear rate conditions will be employed. After that, the interfacial tension between oil and a new polymeric nanofluid at different concentrations and temperatures will be determined using the spinning drop technique. Additionally, wettability alteration behavior will be studied using contact angle (θ) measurements of polymeric fluid on an oil-saturated sandstone surface. Finally, core flooding experiments will be conducted to analyze and compare the ability of novel nano polymeric composites versus conventional polymers in oil recovery under reservoir conditions. The study showed that the optimized polymeric nanoparticle injection increased the recovery factor by 10 %. These findings the use of polymeric nanofluids could be a promising methodology to enhance oil recovery in harsh oil recovery in harsh environments with high temperatures and salinity. By addressing the limitations of polymer flooding and improving the performance of chemical EOR, the application of polymeric nanofluids has the potential to maximize oil production in reservoirs.