A continuous ultrasound assisted process using a single screw extruder with an ultrasonic attachment was developed to prepare polyolefin/clay nanocomposites of varying clay concentrations. Isotactic polypropylene (PP) and high density polyethylene (HDPE) were chosen as a polymeric matrix. A partial intercalation of polymer molecules into clay galleries, which occurs at short residence times (on the order of seconds), was observed, as evident from the measurements by X-ray diffraction and transmission electron microscopy. The obtained results indicated the rapid intercalation of polyolefin/clay nanocomposite without the matrix being chemically modified. Two methods for fabrication of PP/clay nanocomposites using a continuous ultrasound assisted process were compared. In the first approach, where a two stage process was implemented, the nanocomposites were prepared using a co-rotating twin screw extruder followed by a single screw extruder equipped with ultrasonic die attachment.