The incorporation of different percents of titanium dioxide (TiO2) nanoparticles into optically active poly(ester-imide) (PEI), afforded an opportunity to prepare several novel PEI/TiO2 bionanocomposites (BNC)s. To this point, firstly PEI was synthesized via direct polyesterification of chiral diacid monomer and an optically active phenolic diol using tosyl chloride/pyridine/N,N-dimethylformamide system as a condensing agent. Novel BNC polymers containing TiO2 nanoparticles were synthesized through ultrasonic irradiation method. With the aim of gamma-amidopropyl-triethoxylsilicane as a coupling agent, the surface of nanoscale TiO2 was modified to decrease aggregation of nanoparticles in polymer matrix. The obtained PEI/TiO2 BNCs were characterized with FT-IR, thermogravimetric analysis (TGA), scanning electron microscopy, X-ray diffraction, and transmission electron microscopy (TEM) techniques. Consequently, TEM image showed that the nanoparticles of smaller than 50 nm in diameter were uniformly dispersed in the polymer matrix. TGA data demonstrated that new synthesized PEI/TiO2 BNCs are more thermally stable in compare to pure PEI.