The aim of this study was to investigate the effect of ultrasound on the properties of a poly[ethylene-co-(vinyl acetate)] (EVA)-organoclay nanocomposite. By using a torque rheometer, in-situ rheological behaviors of various EVA resins with varying VA content were examined. It was found that the effect of ultrasound was most significant for EVA 31 (31 wt% VA). EVA31/organoclay nanocomposites were prepared in batch mixer with and without irradiation of ultrasound. The characterization of the nanocomposite was performed using XRD, TEM, rheometry, and universal testing machine. XRD and TEM results revealed that the produced EVA31/organoclay nanocomposite with ultrasonic irradiation possessed intercalated structure. Rheometry result indicated that EVA31/organoclay nanocomposite processed with ultrasound had a highly disordered or delaminated structure. A considerable increase in stiffness and Young’s modulus for the sonicated nanocomposite compared to those for unsonicated one was obtained. This study demonstrated the possibility of producing EVA-organoclay nanocomposites with enhanced dispersion of nanoclays using ultrasound assisted processing.