This investigation aims to improve the ultradrawing and ultimate tensile properties of ultrahigh molecular weight polyethylene (UHMWPE) fibers by incorporating small amounts of functionalized activated nanocarbon particles with a wide range of specific surface areas (ca. 100-1,400 m(2)/g) during gel spinning processes of UHMWPE fibers. The ultradrawing, ultimate tensile, orientation properties, and microfibril characteristics of UHMWPE/functionalized activated nanocarbon fibers was discovered to improve considerably with the increase in specific surface areas of functionalized activated nanocarbon. An extraordinary high ultimate tensile strength at 95.8 g/d was obtained for the best prepared UHMWPE/functionalized activated nanocarbon drawn fiber. This value is the highest value ever reported for one-stage drawn UHMWPE fibers and is about 2.9 times that of the UHMWPE drawn fiber prepared in this study. In addition to thermal, ultimate tensile, and orientation factor properties of as-prepared and/or drawn UHMWPE/functionalized activated nanocarbon fibers, specific surface area, Fourier transform infrared, and morphological analyses of original and functionalized activated nanocarbons were performed to comprehend the considerably improved ultradrawing, ultimate tensile properties, and microfibril characteristics of the UHMWPE/functionalized activated nanocarbon fibers. POLYM. ENG. SCI., 58:980-990, 2018. (c) 2017 Society of Plastics Engineers