Novel cellulose nanocrystal (CNC)‐silica (SiO2) nanohybrids with a better thermal stability were successfully fabricated by sol–gel method. In this unique hybrid architecture, it was found that silica particles were uniformly adsorbed/anchored by the CNC via covalent bonding and hydrogen bonding. Subsequently, the nanocomposites containing nanofillers (CNC‐SiO2 nanohybrids or CNC), ultrahigh molecular weight polyethylene (UHMWPE), polyethylene glycol (PEG), were prepared by the twin screw extrusion and their properties and structure were systematically investigated. With the incorporation of CNC‐SiO2 nanohybrids (or CNC) into the UHMWPE matrix, the tensile strength, flexural strength, flexural modulus, vicat softening temperature, and crystallinity of the ensuing nanocomposites were significantly increased. Meanwhile, the nanofiller could enhance the wear resistance of UHMWPE. Notably, compared to CNC, the unique beaded structure of CNC‐SiO2 nanohybrids could endow the UHMWPE with an overall superior performance. POLYM. COMPOS., 39:E1701–E1713, 2018. © 2017 Society of Plastics Engineers