Supramolecular assembled fullerenol/poly(dimethylsiloxane) nanocomposites were prepared from the solution casting of the mixtures of multihydroxylated [60]fullerene (fullerenol) and bis(3-aminopropyl)-terminated poly(dimethylsiloxane) (PDMS-di-NH2) in tetrahydrofuran at different molar ratios. Dynamic light scattering measurements reveal that the fullerenol-PDMS complexes could be formed due to the strong hydrogen bonding interactions between the hydroxyl groups of fullerenol and the amino groups of PDMS-di-NH2. The size and size distribution of the complex particles depend on the molar ratios of OH/NH2 groups and the solution concentrations. Small-angle X-ray scattering results indicate that nanodomains of fullerenol aggregates are confined homogeneously in PDMS matrix. The higher fullerenol content in the composites leads to the larger size of fullerenol nanodomains. This novel structural feature of the nanocomposites together with the unique chemical structure and dielectric property of fullerenol molecules results in superior thermal and thermal mechanical stability, severely suppressed crystalline phase, elastic mechanical response, and attractive dielectric properties of the fullerenol-PDMS nanocomposites; i.e., the high content of fullerenol in the nanocomposites increases the permittivity but dramatically decreases the loss factor of the materials.