This work aims at the preparation of oxidation-resistant copper (Cu) nanoparticles using biocompatible and naturally available polymers such as polyacrylamide and xanthan gum for their possible application in nanofluid and nanohydrogels. Cu nanoparticles as powder were successfully synthesized using a simple chemical reduction technique followed by centrifugation and drying under inert gas environment. The optical properties and morphology of synthesized Cu nanoparticles were characterized using UV-Vis spectrophotometer and transmission electron microscope. TEM images show that the particles are well isolated and vary between 10 and 25 nm in size for both polyacrylamide-and xanthan gum-stabilized Cu nanoparticles. X-ray diffraction studies were also successfully performed to confirm the phase purity of synthesized Cu nanoparticles in terms of surface oxidation. Moreover, nanofluids and nanohydrogels were prepared from the as-synthesized Cu nanoparticles powder and thermophysical and rheological properties were explored successfully. Both polyacrylamideand xanthan gum-capped Cu nanofluids exhibit high stability in terms of aggregation and oxidation for at least 6 months. Approximately 33% enhancement in thermal conductivity was observed for both the nanofluids and the results were consistent with modified Maxwell model. Rheological behaviour of nanofluids and hydrogel was measured and the results suggest that the nanofluid exhibits shear thinning behaviour whereas the nanohydrogel shows viscoelastic behaviour with a gel time of ~2.5 h.