In this study, various optically active poly(ester-amide)/Zinc oxide bionanocomposites (PEA/ZnO BNCs) were synthesized with different amount of modified ZnO nanoparticles using ultrasonic irradiation. To obtain the homogeneous distribution of ZnO in polymer matrix, the surface of nanoparticles was modified to organophile with gamma-aminopropyltriethoxyl silane. PEA/ZnO BNCs were characterized by Fourier transform infrared spectra, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The FE-SEM, AFM, and TEM results confirmed that the nanoparticles were dispersed uniformly in PEA matrix at the nanoscale. In addition, thermogravimetric analysis data indicated an improvement of thermal stability of novel BNC materials as compared to the pure polymer.