Thermal and economic evaluation using covalent functionalized Graphene Nanoplatelets (CF-GNPs) were performed inside a heated-pipe under turbulent conditions. The current nanofluids were produced from CF-GNPs added and distilled water in different mass percentages such as 0.025,0.05,0.075 and 0.1wt.%. The thermal system was under the condition of fully-developed turbulent flow in the range of 6,401 ≤ Re ≤ 11,907 and heated up to 11,205 W/m2. The characterization and morphological properties were done through different examinations and techniques such as zeta potential, nanoparticle sizer, Field Emission Scanning Electron Microscopy (FE-SEM), and Field Emission Transmission Electron Microscope (FE-TEM). Moreover, the economic performance was evaluated to estimate the price-operation of the current thermal system. The heat exchanger size reduced by 16.10%, 21.92%, 25.37% and 29.35% for 0.025wt.%, 0.05wt.%, 0.075wt.% and 0.1wt.%, respectively. Furthermore, the required power for base fluid was 422W then reduced to 354W, 326W, 315W and 298W for 0.025wt.%, 0.05wt.%, 0.075wt.% and 0.1wt.%, respectively.