Bismuth metal nanocrystals were self-assembled into the Bi2Mg2/3Nb4/3O7 (BMNO) dielectric films at room temperature by radio-frequency sputtering for percolative BMNO-Bi nano-composite films. For capacitor applications, BMNO-Bi nano-composite amorphous films sandwiched between protective Al2O3 layers showed an enhanced dielectric permittivity of similar to 220 maintaining an authentic leakage current characteristics, compared with the dielectric permittivity of about 50 observed in the BMNO amorphous films. Moverover, room-temperature grown BMNO-Bi nano-composite films sandwiched between the BMNO protection layers exhibited a high dielectric permittivity of about 310. Enhanced dielectric permittivity of the BMNO-Bi nano-composite films was attributed to a hybrid model that included a space-charge polarization, a dipolar response, and nano-capacitors. The BMNO-Bi composite films exhibiting an enhanced dielectric permittivity can provide an epoch-making breakthrough for the flexible electronic device applications. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.004206jes] All rights reserved.