A novel covalence-linked PMMA-SiO2 hybrid nanodielectrics was prepared by grafting similar to 10 nm PMMA brush onto the SiO2 (similar to 9 nm) surface, which effectively combines the respective merits of PMMA and SiO2. As a result, the hybrid nanodielectrics exhibit excellent dielectric performance (e.g., low leakage density (<10(-7) A/cm(2) at 6 MV/cm), high breakdown voltage (7 MV/cm), high capacitance (142 nF/cm(2)), good operational stability, and good compatibility with organic semiconductors), and enable organic field-effect transistors (OFETs) to work with high performance and low voltage. These results may open a way to build ultrathin dielectrics for high performance transistor and circuit, as well as for microelectronics, nanoelectronics, and organic electronics.