In this study, we synthesized a biodegradable nanocomposite containing starch, polyvinyl alcohol (PVA), and graphene oxide (GO). The non-isothermal degradation kinetics of this nanocomposite was investigated by thermogravimetric analysis. Accordingly, the kinetic parameters, such as activation energy (Ea), exponential factor (A), rate constant (k), and degradation time, were calculated. The calculated kinetic parameters are used to predict the lifetime. The master plot analysis showed that the kinetic function of the thermal degradation changed from A2 to A3 upon addition of GO to the PVA/starch blend. The reaction heat (DH), glass transition temperature (Tg), and melting point (Tm) of the PVA/starch film and PVA/starch/GO nanocomposite were determined by the differential scanning calorimetry analysis. Also, the Tg values were determined by dynamic mechanical thermal analyzer. The changes in peak bandwidth, strength, and frequency in the samples are identified by FTIR spectra. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis and field emission scanning electronic microscope.